Quicksand - fix project board page and quicksand

Summary: Fixes T7913. Collapse the separate board dropdown into the board projects behavior; we always need that anyway and now we can install the listener more granularly.

Test Plan:

• visted project board
• invoked create task, cancelled dialog
• visited project feed
• visited project board
• invoked create task, cancelled dialog (FAILED pre patch...!)

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T7913

Differential Revision: https://secure.phabricator.com/D12599