Use the v3 API, not beta

See
http://developer.github.com/changes/2014-01-07-upcoming-change-to-defaul
t-media-type/
Merge pull request #141 from octokit/v3-media-type

Use the v3 API, not beta
++RAC to fix RACCommand KVO crashes
Merge branch 'master' into rac-3.0

Conflicts:
	External/ReactiveCocoa