add sass support

Change-Id: I90b27b1c574091a12a669b23b97a7730aad6c856
diff --git a/client/webpack.config.js b/client/webpack.config.js
index 84ff411..c02de06 100644
--- a/client/webpack.config.js
+++ b/client/webpack.config.js
@@ -22,8 +22,8 @@
                 }
             },
             {
-                test: /\.css$/i,
-                use: ['style-loader', 'css-loader'],
+                test: /\.s[ac]ss$/i,
+                use: ['style-loader', 'css-loader', 'sass-loader'],
             }
         ]
     },