Use proper loaders for external module's CSS.

- react-toolbox requires its own setup with sass-loader for now
- redux-notifications doen's need to use css-modules
- exclude `node_modules` from our own CSS pipeline

Realted to bcca98b

webpack.base.js

@@ -7,25 +7,37 @@ module.exports = {
   module: {
     loaders: [
       {
-        test: /\.(png|eot|woff|woff2|ttf|svg|gif)(\?v=\d+\.\d+\.\d+)?$/,
-        loader: 'url-loader?limit=10000',
+        loader: 'babel',
+        test: /\.js?$/,
+        exclude: /node_modules/,
       },
       {
-        test: /\.json$/,
-        loader: 'json-loader',
+        /* CSS loader for npm modules that are shipped with CSS.
+           List all of theme in the array
+        */
+        test: /\.css$/,
+        include: [/redux-notifications/],
+        loader: ExtractTextPlugin.extract('style', 'css'),
       },
       {
+        /* React-toolbox still relies on SCSS and css-modules */
         test: /\.scss$/,
+        include: [/react-toolbox/],
         loader: ExtractTextPlugin.extract('style', 'css?modules!sass'),
       },
       {
+        /* We use CSS-modules and PostCSS for CMS styles */
         test: /\.css$/,
+        exclude: /node_modules/,
         loader: ExtractTextPlugin.extract('style', 'css?modules&importLoaders=1&&localIdentName=cms__[name]__[local]!postcss'),
       },
       {
-        loader: 'babel',
-        test: /\.js?$/,
-        exclude: /node_modules/,
+        test: /\.(png|eot|woff|woff2|ttf|svg|gif)(\?v=\d+\.\d+\.\d+)?$/,
+        loader: 'url-loader?limit=10000',
+      },
+      {
+        test: /\.json$/,
+        loader: 'json-loader',
       },
     ],
   },