R1:5945546440a3

Unify Differential/Maniphest/Diffusion styles and allow commits to be flagged explicitly

Summary:
- Differential, Maniphest and Diffusion use slightly different styles for the object detail panels.
- Instead, use the same styles and CSS.
- Add object actions to Diffusion, including "Flag".

Test Plan: Looked at revisions, tasks and commit. Flagged and unflagged commits.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran, epriestley

Maniphest Tasks: T1041

Differential Revision: https://secure.