R1:29cfcc82ef7f

Update Milestone/Subproject page

Summary: Cleans up the UI, moves details over to curtain, adds some fallback no data strings.

Test Plan: Review with and without subprojects, milestones.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D17907