improve app menu code + es6-ify main.js
improve app menu code + es6-ify main.js

blckt/electron,blckt/electron,onehungrymind/electrogram,Infining/angular2-webpack-electron,onehungrymind/electrogram,Infining/angular2-webpack-electron,onehungrymind/electrogram,Infining/angular2-webpack-electron