Make sure module can be required in Node.js without throwing an error…

… (needed for universal / SSR builds)

webpack.config.js

@@ -74,6 +74,7 @@ function getPluginsForConfig(type, minify = false) {
   );
 
   const plugins = [
+    new webpack.BannerPlugin({ entryOnly: true, raw: true, banner: 'typeof window !== "undefined" &&' }), // SSR/Node.js guard
     new webpack.optimize.OccurrenceOrderPlugin(),
     new webpack.DefinePlugin(defineConstants)
   ];