chore(package): update node-sass to version 4.5.0

Closes #1210

https://greenkeeper.io/

Author: greenkeeper[bot]

package.json

@@ -132,7 +132,7 @@
     "gemini-browserstack": "1.0.0",
     "imports-loader": "0.7.0",
     "nightwatch": "0.9.12",
-    "node-sass": "3.13.1",
+    "node-sass": "4.5.0",
     "nodemon": "1.11.0",
     "phantomjs-prebuilt": "2.1.14",
     "postcss-loader": "1.2.2",