Use babel for ES6 / ES2015 support

webpack.config.js

@@ -15,6 +15,13 @@ module.exports = {
     },
     module: {
         loaders: [
+            {
+                test: /\.js$/,
+                loader: 'babel-loader',
+                query: {
+                    presets: ['es2015']
+                }
+            },
             {
                 test: /\.json$/,
                 loader: 'json-loader'