Add YUIDoc to the mix? 

I've been doing a lot of documentation-based projects recently, and find that YUIDoc is a great choice for Ember projects since core uses it anyway.

The [grunt-contrib-yuidoc](https://github.com/gruntjs/grunt-contrib-yuidoc) plays nicely as an addition, and is actively maintained.

Also, the [yuidoc-theme-blue](https://github.com/royriojas/yuidoc-theme-blue) is pretty nice as an alternative to the default theme, so I went ahead and threw that onboard.

The docs can be built using just:

````
grunt
````

... or specifically:

````
grunt docs
````

... and also runs with the `grunt-contrib-watch` task when developing with:

````
grunt server
````

Anyway, I think YUIDoc would be a great addition to ember-app-kit.