add es3-safe-transpile step

currently:

```js
promise.finally -> promise[‘finally’]
promise.catch   -> promise[‘catch’]
a.default       -> a[‘default’]
// and some more..
```

see: https://github.com/stefanpenner/es3-safe-recast for more
Included broccoli-asset-rev for fingerprinting.
Merge pull request #814 from rickharrison/broccoli-asset-rev

Included broccoli-asset-rev for fingerprinting in EmberApp
Ember-Data Beta 8
Merge pull request #855 from bcardarella/bc-ember-beta-data-8

Ember-Data Beta 8
Merge pull request #823 from stefanpenner/es3-safe

add es3-safe-transpile step
Changes `ember-app` helper's behavior

Takes away an option to specify an app's name through `ember-app`
helper. App's name is taken from `package.json`.

Fixes #827