chore(package): update webpack-dev-server to version 3.3.1

Closes #17

Author: greenkeeper[bot]

package.json

@@ -43,7 +43,7 @@
     "uglifyjs-webpack-plugin": "^2.0.0",
     "webpack": "4.17.0",
     "webpack-cli": "3.1.0",
-    "webpack-dev-server": "3.1.6"
+    "webpack-dev-server": "3.3.1"
   },
   "dependencies": {
     "@uirouter/angularjs": "1.0.20",