chore(package): update webpack to version 4.42.0

Closes #290

Author: greenkeeper[bot]

package.json

@@ -61,7 +61,7 @@
     "react-router": "^3.0.4",
     "react-test-renderer": "^15.6.1",
     "sinon": "2.3.8",
-    "webpack": "3.3.0",
+    "webpack": "4.42.0",
     "webpack-dev-server": "2.6.1"
   },
   "peerDependencies": {