Make "Assign / Claim" stacked action work properly in Maniphest
I think I've fixed it enough that the beahavior is now correct (i.e., icons show up properly), but some of the code is a bit iffy. I'll eventually clean this up properly, but it's fairly well contained for now.
- Reassigned a task.
- Put a task up for grabs.
- No reassign on closed tasks.
Reviewed By: chad
Maniphest Tasks: T9132
Differential Revision: https://secure.phabricator.com/D14669