dropped node 0.12 support, now using yarn instead npm for scripts and travis-ci testing

src/JavaScriptObfuscator.ts

@@ -1,9 +1,5 @@
 import 'reflect-metadata';
 
-if (!(<any>global)._babelPolyfill && parseInt(process.version.split('.')[0], 10) < 4) {
-    require('babel-polyfill');
-}
-
 import { ServiceIdentifiers } from './container/ServiceIdentifiers';
 
 import { TInputOptions } from './types/options/TInputOptions';