Github hooks fixed, rubygems integrated in

Changed the model structure so that a Plugin has both one GithubRepo and one RubyGem, each of those having lots of updates.  Adding a hook to one should find the other when it's first hook is sent.

On the timeline, the updates (new commits, new gem versions) are shown interleaved.

See a demo at http://justinaiken.com:4567/

Also includes:

- Tests
- A Style fix
- Structural refactors (closer to a rails-like structure)
- Layout refactors