Initial code splitting

index.diff

import Backbone from 'backbone';
import $ from 'jquery';

import Router from './router';
- import AboutApp from './apps/about/';
- import HeavyApp from './apps/heavy/';

$(() => {
  new Router();
- AboutApp();
- HeavyApp();
+ require.ensure([], require => {
+   const AboutApp = require('./apps/about/').default;
+   AboutApp();
+ });
+ require.ensure([], require => {
+  const HeavyApp = require('./apps/heavy/').default;
+  HeavyApp();
+ });

  Backbone.history.start();
});