chore(package): update babel-core to version 6.20.0 (#365)

package.json

@@ -52,7 +52,7 @@
   },
   "dependencies": {
     "ansi-html": "0.0.6",
-    "babel-core": "6.18.2",
+    "babel-core": "6.20.0",
     "babel-generator": "6.20.0",
     "babel-loader": "6.2.8",
     "babel-plugin-module-resolver": "2.4.0",