Use a list view for DiffusionHistory

Summary: This moves Diffusion History to use an easier to parse list view for commits and their (diff, audit, build) status. I left TableView around, which is used on a repositories home, and we can maybe add a "graph view" history back as another controller. Not sure what the real use is for that kind of feature though. I don't have Harbormaster set up locally so I could use another install to give this a run. I also expect to maybe not live with this UI as final, I like the UX, but the icons for indicating status don't really feel great to me, just OK.

Test Plan:
pull various repositories, check various history displays.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D18039