Add Peer Dependencies to package.json

[kylefinley]

Once Brunch 1.7.0 is released, add peer dependencies.
Reevaluate issue #13 - Brunch as a dependency

http://blog.nodejs.org/2013/02/07/peer-dependencies/

brunch/brunch#628

[es128]

You can probably close this. Turns out the original idea won't work for skeletons.

On the bright side, brunch as a dependency will now become a more standard design pattern with brunch/brunch#634

[kylefinley]

Oh, OK, thanks Elan.