chore(package): update babel-core to version 6.9.1 (#776)

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -10,7 +10,7 @@
   "devDependencies": {
     "async": "~2.0.0-rc.5",
     "babel": "~6.5.2",
-    "babel-core": "~6.9.0",
+    "babel-core": "~6.9.1",
     "babel-loader": "~6.2.4",
     "babel-preset-es2015": "~6.9.0",
     "babelify": "~7.3.0",