switch composer to interfaces v2 and commons v3

Removed sudo from travis config and added os linux.

Author: gregor-j

.travis.yml

@@ -1,5 +1,5 @@
 language: php
-sudo: false
+os: linux
 php:
   - 7.0
   - 7.1

composer.json

@@ -23,7 +23,7 @@
     "kralik"
   ],
   "provide": {
-    "php-sap/interfaces": "v2.x-dev"
+    "php-sap/interfaces": "^2.0"
   },
   "conflict": {
     "kba-team/php-sapnwrfc-kralik": "*",
@@ -34,13 +34,13 @@
   "require": {
     "php": "^7.0",
     "ext-sapnwrfc": "*",
-    "php-sap/interfaces": "v2.x-dev",
-    "php-sap/common": "v3.x-dev"
+    "php-sap/interfaces": "^2.0",
+    "php-sap/common": "^3.0"
   },
   "require-dev": {
     "ext-json": "*",
     "phpunit/phpunit": "^6.5",
-    "php-sap/integration-tests": "dev-master-v4"
+    "php-sap/integration-tests": "^4.0"
   },
   "autoload": {
     "psr-4": {