ProjectView improvements

Summary: Simplified header, added Workboard button and icon, moved Maniphest actions to "Open Tasks" Object Box. Reduced actions by 3.

Test Plan: Test a number of project pages, looks better, cleaner.

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D8219