chore(package): update babel-core to version 6.18.0

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -38,7 +38,7 @@
   },
   "devDependencies": {
     "babel-cli": "^6.7.7",
-    "babel-core": "^6.7.7",
+    "babel-core": "^6.18.0",
     "babel-eslint": "^7.0.0",
     "babel-preset-es2015": "^6.6.0",
     "code": "^3.0.0",