Update blame view in Diffusion
Summary: Ref T12824, adds more information to the blame view, exposes date, commit summary, lighter colors.
Test Plan:
Review many diffs with and without blame on.
Reviewers: epriestley
Reviewed By: epriestley
Spies: Korvin
Maniphest Tasks: T12824
Differential Revision: https://secure.phabricator.com/D18452