Brings EAK grunt setup into ember-cli

At this point I have very basic versions of build & server both working against the basic EAK scaffold. I'd like to start testing this now and figuring out where we need to make it configurable.

To build, run:

    ember build <environment: development|production>

To fire up a preview server run:

    ember server [-e development|production]

I've tried to keep the grunt stuff decoupled as much as possible from the CLI; hopefully this will make integrating broccoli easier, and give us something that we can use while that work is being done.

What do you think, @stefanpenner? Is this good enough to get an initial merge?