Change CLOSED colors to Indigo over Black

Summary: CLosed is a pretty important state and black tends to blend in a bit. This bumps to an alternate color to improve ability to scan and know state of objects.

Test Plan:
Review a number of closed objects. I will follow up with another diff on 'Archived' colors.

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11222