Summary: I didn't get around to this earlier; add Feed/Maniphest integration.
This is partly motivated by wanting Projects to not be terrible. Pretty
straightforward.
Test Plan:
- Created, updated, reassigned and closed a task.
- Verified feed stories render reasonably.
Reviewers: btrahan, jungejason
Reviewed By: btrahan
CC: aran, btrahan
Maniphest Tasks: T681
Differential Revision: 1232
