jspm compatibility

This PR enables installation through jspm: `jspm install ember=github:components/ember`

Using it is quite easy: Type the command above and create these two files
``` HTML
<!-- index.html -->
<script src="jspm_packages/system.js"></script>
<script src="config.js"></script>
<script>
  System.import('main').catch(console.error.bind(console))
</script>
```

``` JavaScript
// main.js
import Ember from 'ember'
Ember.Application.create()
```
Only master has the jspm compatibility in it. `2.0.0` doesn't, the next release will of course.