Show projects on Maniphest tasks

Summary:

• Remove the "Priority" column, since this is indicated by the color swatch, to save space.
• Reduce the "Updated" column from datetime to date only, since time isn't incredibly useful, to save space.
• Show the first two projects a task is associated with, and "..." if there are more.
• Show "None" (for "no owner") in a lighter color.

Test Plan: Looked at tasks on homepage and in Maniphest.

Reviewers: btrahan, 20after4

Reviewed By: btrahan

CC: aran, edward

Maniphest Tasks: T967

Differential Revision: https://secure.phabricator.com/D2065