Merge pull request #1504 from mozilla/greenkeeper/node-sass-4.1.0

Update node-sass to the latest version 🚀

package.json

@@ -234,7 +234,7 @@
     "karma-sourcemap-loader": "0.3.7",
     "karma-webpack": "1.8.0",
     "mocha": "3.2.0",
-    "node-sass": "3.13.1",
+    "node-sass": "4.1.0",
     "po2json": "0.4.5",
     "postcss-loader": "1.2.1",
     "react-addons-test-utils": "15.4.1",