chore(package): update webpack-dev-middleware to version 2.0.4

Closes #39

Author: greenkeeper[bot]

package.json

@@ -59,7 +59,7 @@
     "style-loader": "^0.16.1",
     "surge": "^0.19.0",
     "webpack": "^2.3.3",
-    "webpack-dev-middleware": "^1.10.1",
+    "webpack-dev-middleware": "^2.0.4",
     "webpack-hot-middleware": "^2.18.0",
     "webpack-md5-hash": "0.0.5"
   }