Soft-launch project boards

Summary: Ref T1344. I don't think we'll need to destroy any data moving forward, and would like to get more feedback about what changes users want.

Test Plan: Looked at a project and clicked onto its board.

Reviewers: chad, btrahan

Reviewed By: chad

CC: aran

Maniphest Tasks: T1344

Differential Revision: https://secure.phabricator.com/D8191