Please update the Hello World example and include more usage examples as well

[kristianmandrup]

Currently it contains this:

Register Bootstrap for Ember components [I DONT THINK WE NEED THIS ANYMORE?]

Open app.js and change:

App = Ember.Application.create();

TO:

`App = Ember.Application.createWithMixins(Bootstrap);``

However, using ember cli (recommended), creates an app.js file like this:

import Ember from 'ember';
import Resolver from 'ember/resolver';
import loadInitializers from 'ember/load-initializers';

Ember.MODEL_FACTORY_INJECTIONS = true;

var App = Ember.Application.extend({
  modulePrefix: 'demo-app', // TODO: loaded via config
  Resolver: Resolver
});

loadInitializers(App, 'demo-app');

export default App;

and in index.html the App object is created

    <script>
      window.DemoApp = require('demo-app/app')['default'].create(DemoAppENV.APP);
    </script>