chore(package): update webpack to version 4.0.0

Author: greenkeeper[bot]

package.json

@@ -91,7 +91,7 @@
     "tslint-eslint-rules": "^5.0.0",
     "tslint-loader": "^3.5.3",
     "typescript": "^2.7.2",
-    "webpack": "^3.11.0",
+    "webpack": "^4.0.0",
     "webpack-dev-server": "^2.11.1"
   },
   "dependencies": {