Remove Dedupe plugin from webpack

https://webpack.github.io/docs/list-of-plugins.html#dedupeplugin – it's still experimental. This allows `make watch` to update correctly.

webpack.config.js

@@ -60,7 +60,6 @@ module.exports = {
                 warnings: false
             }
         }),
-        new webpack.optimize.OccurenceOrderPlugin(),
-        new webpack.optimize.DedupePlugin()
+        new webpack.optimize.OccurenceOrderPlugin()
     ]
 };