diff --git a/package-lock.json b/package-lock.json
index a283c64..0a7a7ea 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -224,14 +224,21 @@
       "integrity": "sha1-4h3xCtbCBTKVvLuNq0Cwnb6ofk0="
     },
     "ajv": {
-      "version": "6.10.2",
-      "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.10.2.tgz",
-      "integrity": "sha512-TXtUUEYHuaTEbLZWIKUr5pmBuhDLy+8KYtPYdcV8qC+pOZL+NKqYwvWSRrVXHn+ZmRRAu8vJTAznH7Oag6RVRw==",
+      "version": "6.12.6",
+      "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.12.6.tgz",
+      "integrity": "sha512-j3fVLgvTo527anyYyJOGTYJbG+vnnQYvE0m5mmkc1TK+nxAppkCLMIL0aZ4dblVCNoGShhm+kzE4ZUykBoMg4g==",
       "requires": {
-        "fast-deep-equal": "^2.0.1",
+        "fast-deep-equal": "^3.1.1",
         "fast-json-stable-stringify": "^2.0.0",
         "json-schema-traverse": "^0.4.1",
         "uri-js": "^4.2.2"
+      },
+      "dependencies": {
+        "fast-deep-equal": {
+          "version": "3.1.3",
+          "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",
+          "integrity": "sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q=="
+        }
       }
     },
     "ansi-regex": {
@@ -1499,11 +1506,6 @@
       "resolved": "https://registry.npmjs.org/extsprintf/-/extsprintf-1.3.0.tgz",
       "integrity": "sha1-lpGEQOMEGnpBT4xS48V06zw+HgU="
     },
-    "fast-deep-equal": {
-      "version": "2.0.1",
-      "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-2.0.1.tgz",
-      "integrity": "sha1-ewUhjd+WZ79/Nwv3/bLLFf3Qqkk="
-    },
     "fast-json-stable-stringify": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/fast-json-stable-stringify/-/fast-json-stable-stringify-2.0.0.tgz",
diff --git a/yarn.lock b/yarn.lock
index 47c9562..9d5701e 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -168,11 +168,11 @@ aes-js@3.0.0:
   integrity sha1-4h3xCtbCBTKVvLuNq0Cwnb6ofk0=
 
 ajv@^6.5.5:
-  version "6.10.2"
-  resolved "https://registry.yarnpkg.com/ajv/-/ajv-6.10.2.tgz#d3cea04d6b017b2894ad69040fec8b623eb4bd52"
-  integrity sha512-TXtUUEYHuaTEbLZWIKUr5pmBuhDLy+8KYtPYdcV8qC+pOZL+NKqYwvWSRrVXHn+ZmRRAu8vJTAznH7Oag6RVRw==
+  version "6.12.6"
+  resolved "https://registry.yarnpkg.com/ajv/-/ajv-6.12.6.tgz#baf5a62e802b07d977034586f8c3baf5adf26df4"
+  integrity sha512-j3fVLgvTo527anyYyJOGTYJbG+vnnQYvE0m5mmkc1TK+nxAppkCLMIL0aZ4dblVCNoGShhm+kzE4ZUykBoMg4g==
   dependencies:
-    fast-deep-equal "^2.0.1"
+    fast-deep-equal "^3.1.1"
     fast-json-stable-stringify "^2.0.0"
     json-schema-traverse "^0.4.1"
     uri-js "^4.2.2"
@@ -316,20 +316,40 @@ bech32@^1.1.3:
   resolved "https://registry.yarnpkg.com/bech32/-/bech32-1.1.3.tgz#bd47a8986bbb3eec34a56a097a84b8d3e9a2dfcd"
   integrity sha512-yuVFUvrNcoJi0sv5phmqc6P+Fl1HjRDRNOOkHY2X/3LBy2bIGNSFx4fZ95HMaXHupuS7cZR15AsvtmCIF4UEyg==
 
+big-number@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/big-number/-/big-number-2.0.0.tgz#98548eda9393b445791670a213aed6f6dcd66ee3"
+  integrity sha512-C67Su0g+XsmXADX/UM9L/+xSbqqwq0D/qGJs2ky6Noy2FDuCZnC38ZSXODiaBvqWma2VYRZEXgm4H74PS6tCDg==
+
 big.js@^5.2.2:
   version "5.2.2"
   resolved "https://registry.yarnpkg.com/big.js/-/big.js-5.2.2.tgz#65f0af382f578bcdc742bd9c281e9cb2d7768328"
   integrity sha512-vyL2OymJxmarO8gxMr0mhChsO9QGwhynfuu4+MHTAW6czfq9humCB7rKpUjDd9YUiDPU4mzpyupFSvOClAwbmQ==
 
+bignumber-to-string@^0.1.4:
+  version "0.1.4"
+  resolved "https://registry.yarnpkg.com/bignumber-to-string/-/bignumber-to-string-0.1.4.tgz#9c47a994d37042b4062a135c0c19c703a81e634d"
+  integrity sha1-nEeplNNwQrQGKhNcDBnHA6geY00=
+
 bignumber.js@^7.2.1:
   version "7.2.1"
   resolved "https://registry.yarnpkg.com/bignumber.js/-/bignumber.js-7.2.1.tgz#80c048759d826800807c4bfd521e50edbba57a5f"
   integrity sha512-S4XzBk5sMB+Rcb/LNcpzXr57VRTxgAvaAEDAl1AwRx27j00hT84O6OkteE7u8UB3NuaaygCRrEpqox4uDOrbdQ==
 
+bignumber.js@^9.0.0:
+  version "9.0.2"
+  resolved "https://registry.yarnpkg.com/bignumber.js/-/bignumber.js-9.0.2.tgz#71c6c6bed38de64e24a65ebe16cfcf23ae693673"
+  integrity sha512-GAcQvbpsM0pUb0zw1EI0KhQEZ+lRwR5fYaAp3vPOYuP7aDvGy6cVN6XHLauvF8SOga2y0dcLcjt3iQDTSEliyw==
+
 "bignumber.js@git+https://github.com/debris/bignumber.js.git#94d7146671b9719e00a09c29b01a691bc85048c2":
   version "2.0.7"
   resolved "git+https://github.com/debris/bignumber.js.git#94d7146671b9719e00a09c29b01a691bc85048c2"
 
+bignumber@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/bignumber/-/bignumber-1.1.0.tgz#e6ab0a743da5f3ea018e5c17597d121f7868c159"
+  integrity sha1-5qsKdD2l8+oBjlwXWX0SH3howVk=
+
 bindings@^1.2.1, bindings@^1.3.0, bindings@^1.4.0, bindings@^1.5.0:
   version "1.5.0"
   resolved "https://registry.yarnpkg.com/bindings/-/bindings-1.5.0.tgz#10353c9e945334bc0511a6d90b38fbc7c9c504df"
@@ -1314,15 +1334,15 @@ extsprintf@^1.2.0:
   resolved "https://registry.yarnpkg.com/extsprintf/-/extsprintf-1.4.0.tgz#e2689f8f356fad62cca65a3a91c5df5f9551692f"
   integrity sha1-4mifjzVvrWLMplo6kcXfX5VRaS8=
 
-fast-deep-equal@^2.0.1:
-  version "2.0.1"
-  resolved "https://registry.yarnpkg.com/fast-deep-equal/-/fast-deep-equal-2.0.1.tgz#7b05218ddf9667bf7f370bf7fdb2cb15fdd0aa49"
-  integrity sha1-ewUhjd+WZ79/Nwv3/bLLFf3Qqkk=
+fast-deep-equal@^3.1.1:
+  version "3.1.3"
+  resolved "https://registry.yarnpkg.com/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz#3a7d56b559d6cbc3eb512325244e619a65c6c525"
+  integrity sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q==
 
 fast-json-stable-stringify@^2.0.0:
-  version "2.0.0"
-  resolved "https://registry.yarnpkg.com/fast-json-stable-stringify/-/fast-json-stable-stringify-2.0.0.tgz#d5142c0caee6b1189f87d3a76111064f86c8bbf2"
-  integrity sha1-1RQsDK7msRifh9OnYREGT4bIu/I=
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/fast-json-stable-stringify/-/fast-json-stable-stringify-2.1.0.tgz#874bf69c6f404c2b5d99c481341399fd55892633"
+  integrity sha512-lhd/wF+Lk98HZoTCtlVraHtfh5XYijIjalXck7saUtuanSDyLMxnHhSXEDJqHxD7msR8D0uCmqlkwjCV8xvwHw==
 
 fd-slicer@~1.1.0:
   version "1.1.0"
@@ -1657,6 +1677,11 @@ hash.js@^1.0.0, hash.js@^1.0.3:
     inherits "^2.0.3"
     minimalistic-assert "^1.0.1"
 
+hex64@^0.4.0:
+  version "0.4.0"
+  resolved "https://registry.yarnpkg.com/hex64/-/hex64-0.4.0.tgz#ad1078ac81d57d72de6232b1003bc4f6fb0287c0"
+  integrity sha1-rRB4rIHVfXLeYjKxADvE9vsCh8A=
+
 hmac-drbg@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/hmac-drbg/-/hmac-drbg-1.0.1.tgz#d2745701025a6c775a6c545793ed502fc0c649a1"
@@ -1913,6 +1938,13 @@ jsbn@~0.1.0:
   resolved "https://registry.yarnpkg.com/jsbn/-/jsbn-0.1.1.tgz#a5e654c2e5a2deb5f201d96cefbca80c0ef2f513"
   integrity sha1-peZUwuWi3rXyAdls77yoDA7y9RM=
 
+json-bigint@^0.3.0:
+  version "0.3.1"
+  resolved "https://registry.yarnpkg.com/json-bigint/-/json-bigint-0.3.1.tgz#0c1729d679f580d550899d6a2226c228564afe60"
+  integrity sha512-DGWnSzmusIreWlEupsUelHrhwmPPE+FiQvg+drKfk2p+bdEYa5mp4PJ8JsCWqae0M2jQNb0HPvnwvf1qOTThzQ==
+  dependencies:
+    bignumber.js "^9.0.0"
+
 json-buffer@3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/json-buffer/-/json-buffer-3.0.0.tgz#5b1f397afc75d677bde8bcfc0e47e1f9a3d9a898"
@@ -1994,6 +2026,11 @@ lodash@4, lodash@^4.17.11, lodash@^4.17.14, lodash@^4.17.15:
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.15.tgz#b447f6670a0455bbfeedd11392eff330ea097548"
   integrity sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==
 
+lodash@^4.17.19:
+  version "4.17.21"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.21.tgz#679591c564c3bffaae8454cf0b3df370c3d6911c"
+  integrity sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg==
+
 loom-js@^1.40.0:
   version "1.55.0"
   resolved "https://registry.yarnpkg.com/loom-js/-/loom-js-1.55.0.tgz#283d3e20a2b3b01d6c00015f874f0fe49cfc820f"
@@ -2543,6 +2580,11 @@ psl@^1.1.24:
   resolved "https://registry.yarnpkg.com/psl/-/psl-1.4.0.tgz#5dd26156cdb69fa1fdb8ab1991667d3f80ced7c2"
   integrity sha512-HZzqCGPecFLyoRj5HLfuDSKYTJkAfB5thKBIkRHtGjWwY7p1dAyveIbXIq4tO0KYfDF2tHqPUgY9SDnGm00uFw==
 
+psl@^1.1.28:
+  version "1.8.0"
+  resolved "https://registry.yarnpkg.com/psl/-/psl-1.8.0.tgz#9326f8bcfb013adcc005fdff056acce020e51c24"
+  integrity sha512-RIdOzyoavK+hA18OGGWDqUTsCLhtA7IcZ/6NCs4fFJaHBDab+pDDmDIByWFRQJq2Cd7r1OoQxBGKOaztq+hjIQ==
+
 public-encrypt@^4.0.0:
   version "4.0.3"
   resolved "https://registry.yarnpkg.com/public-encrypt/-/public-encrypt-4.0.3.tgz#4fcc9d77a07e48ba7527e7cbe0de33d0701331e0"
@@ -2595,7 +2637,7 @@ punycode@^1.4.1:
   resolved "https://registry.yarnpkg.com/punycode/-/punycode-1.4.1.tgz#c0d5a63b2718800ad8e1eb0fa5269c84dd41845e"
   integrity sha1-wNWmOycYgArY4esPpSachN1BhF4=
 
-punycode@^2.1.0:
+punycode@^2.1.0, punycode@^2.1.1:
   version "2.1.1"
   resolved "https://registry.yarnpkg.com/punycode/-/punycode-2.1.1.tgz#b58b010ac40c22c5657616c8d2c2c02c7bf479ec"
   integrity sha512-XRsRjdf+j5ml+y/6GKHPZbrF/8p2Yga0JPtdqTIY2Xe5ohJPD9saDJJLPvp9+NSBprVvevdXZybnj2cv8OEd0A==
@@ -2708,6 +2750,23 @@ regenerator-runtime@^0.13.2:
   resolved "https://registry.yarnpkg.com/regenerator-runtime/-/regenerator-runtime-0.13.3.tgz#7cf6a77d8f5c6f60eb73c5fc1955b2ceb01e6bf5"
   integrity sha512-naKIZz2GQ8JWh///G7L3X6LaQUAMp2lvb1rvwwsURe/VXwD6VMfr+/1NuNw3ag8v2kY1aQ/go5SNn79O9JU7yw==
 
+request-promise-core@1.1.4:
+  version "1.1.4"
+  resolved "https://registry.yarnpkg.com/request-promise-core/-/request-promise-core-1.1.4.tgz#3eedd4223208d419867b78ce815167d10593a22f"
+  integrity sha512-TTbAfBBRdWD7aNNOoVOBH4pN/KigV6LyapYNNlAPA8JwbovRti1E88m3sYAwsLi5ryhPKsE9APwnjFTgdUjTpw==
+  dependencies:
+    lodash "^4.17.19"
+
+request-promise@^4.2.5:
+  version "4.2.6"
+  resolved "https://registry.yarnpkg.com/request-promise/-/request-promise-4.2.6.tgz#7e7e5b9578630e6f598e3813c0f8eb342a27f0a2"
+  integrity sha512-HCHI3DJJUakkOr8fNoCc73E5nU5bqITjOYFMDrKHYOXWXrgD/SBaC7LjwuPymUprRyuF06UK7hd/lMHkmUXglQ==
+  dependencies:
+    bluebird "^3.5.0"
+    request-promise-core "1.1.4"
+    stealthy-require "^1.1.1"
+    tough-cookie "^2.3.3"
+
 request@^2.79.0:
   version "2.88.0"
   resolved "https://registry.yarnpkg.com/request/-/request-2.88.0.tgz#9c2fca4f7d35b592efe57c7f0a55e81052124fef"
@@ -3030,6 +3089,11 @@ sshpk@^1.7.0:
   resolved "https://registry.yarnpkg.com/statuses/-/statuses-1.5.0.tgz#161c7dac177659fd9811f43771fa99381478628c"
   integrity sha1-Fhx9rBd2Wf2YEfQ3cfqZOBR4Yow=
 
+stealthy-require@^1.1.1:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/stealthy-require/-/stealthy-require-1.1.1.tgz#35b09875b4ff49f26a777e509b3090a3226bf24b"
+  integrity sha1-NbCYdbT/SfJqd35QmzCQoyJr8ks=
+
 steno@^0.4.1:
   version "0.4.4"
   resolved "https://registry.yarnpkg.com/steno/-/steno-0.4.4.tgz#071105bdfc286e6615c0403c27e9d7b5dcb855cb"
@@ -3298,6 +3362,14 @@ toidentifier@1.0.0:
   resolved "https://registry.yarnpkg.com/toidentifier/-/toidentifier-1.0.0.tgz#7e1be3470f1e77948bc43d94a3c8f4d7752ba553"
   integrity sha512-yaOH/Pk/VEhBWWTlhI+qXxDFXlejDGcQipMlyxda9nthulaxLZUNcUqFxokp0vcYnvteJln5FNQDRrxj3YcbVw==
 
+tough-cookie@^2.3.3:
+  version "2.5.0"
+  resolved "https://registry.yarnpkg.com/tough-cookie/-/tough-cookie-2.5.0.tgz#cd9fb2a0aa1d5a12b473bd9fb96fa3dcff65ade2"
+  integrity sha512-nlLsUzgm1kfLXSXfRZMc1KLAugd4hqJHDTvc2hDIwS3mZAfMEuMbc03SujMF+GEcpaX/qboeycw6iO8JwVv2+g==
+  dependencies:
+    psl "^1.1.28"
+    punycode "^2.1.1"
+
 tough-cookie@~2.4.3:
   version "2.4.3"
   resolved "https://registry.yarnpkg.com/tough-cookie/-/tough-cookie-2.4.3.tgz#53f36da3f47783b0925afa06ff9f3b165280f781"
@@ -3424,9 +3496,9 @@ unpipe@1.0.0, unpipe@~1.0.0:
   integrity sha1-sr9O6FFKrmFltIF4KdIbLvSZBOw=
 
 uri-js@^4.2.2:
-  version "4.2.2"
-  resolved "https://registry.yarnpkg.com/uri-js/-/uri-js-4.2.2.tgz#94c540e1ff772956e2299507c010aea6c8838eb0"
-  integrity sha512-KY9Frmirql91X2Qgjry0Wd4Y+YTdrdZheS8TFwvkbLWf/G5KNJDCh6pKL5OZctEW4+0Baa5idK2ZQuELRwPznQ==
+  version "4.4.1"
+  resolved "https://registry.yarnpkg.com/uri-js/-/uri-js-4.4.1.tgz#9b1a52595225859e55f669d928f88c6c57f2a77e"
+  integrity sha512-7rKUyy33Q1yc98pQ1DAmLtwX109F7TIfWlW1Ydo8Wl1ii1SeHieeh0HHfPeL2fMXK6z0s8ecKs9frCuLJvndBg==
   dependencies:
     punycode "^2.1.0"
 
@@ -4144,3 +4216,8 @@ yauzl@^2.4.2:
   dependencies:
     buffer-crc32 "~0.2.3"
     fd-slicer "~1.1.0"
+
+zeppelin-solidity@^1.12.0:
+  version "1.12.0"
+  resolved "https://registry.yarnpkg.com/zeppelin-solidity/-/zeppelin-solidity-1.12.0.tgz#427edf8e0041ec8600875d3cb8fc9395f33ccfff"
+  integrity sha512-dgjPPnTmx14hAbTeOpTKemDeDCDdwglS0nquOAJG8h5o9zlb43FZafQSrMlIUUSp1EisDZfehrp5loGEYXHZBA==