Allow automatic SSH key association when adding/editing GitHub repositories

Review Request #3423 — Created Oct. 16, 2012 and submitted — Latest diff uploaded

Information

Review Board
master

Reviewers

Defines an interface to allow a Review Board instance's SSH key to be added to
a hosting service's list of deploy keys for a given repository. So far, only 
the GitHub HostingService implements the necessary methods to upload the SSH
key, and raises an exception when the upload fails. The code is not currently
being used by any module/app other than tests.
Unit test for GitHub auto key association passes. Tested that key is delivered
and added to the deploy keys of a GitHub project.