Use babel-polyfill package instead of babel/polyfill

Author: tonyganch

package.json

@@ -10,6 +10,7 @@
   },
   "devDependencies": {
     "babel": "^5.5.3",
+    "babel-polyfill": "^6.9.1",
     "jscs": "1.13.x",
     "jshint": "2.8.x",
     "mocha": "1.20.x",

src/core.js

@@ -1,6 +1,4 @@
-if (!global._babelPolyfill) {
-  require('babel/polyfill');
-}
+require('babel-polyfill');
 let fs = require('fs');
 let gonzales = require('gonzales-pe');
 let minimatch = require('minimatch');