Stubbed out some Ember CLI documentation (content copied directly from http://www.ember-cli.com). Does this look good? If so, I can fix the formatting and dump the rest of the pages.

I'd really like to help update the documentation to be more Ember CLI focused. After there's a good amount of docs on Ember CLI, the older content (ex: the TODO app using Ember 1.3) can be removed from the guide section of this project.