feat(package): update node-sass to version 4.0.0 (#20)

BREAKING CHANGE: node-sass is now at 4.0.0

Author: greenkeeperio-bot

package.json

@@ -47,7 +47,7 @@
   },
   "dependencies": {
     "@easy-webpack/config-css": "^4.0.0",
-    "node-sass": "^3.10.1",
+    "node-sass": "^4.0.0",
     "sass-loader": "^4.0.2"
   },
   "peerDependencies": {