chore(package): update eslint to version 5.15.3

Closes #10

Author: greenkeeper[bot]

Diff for: package.json

@@ -53,7 +53,7 @@
   },
   "devDependencies": {
     "babel-eslint": "^8.0.0",
-    "eslint": "^4.7.2",
+    "eslint": "^5.15.3",
     "eslint-plugin-react": "^7.3.0",
     "nwb": "^0.21.1",
     "prettier": "^1.7.0",