R1:ded034474597

Have milestones inherit colors from parent projects

Summary: Fixes T10737. I agree that this is a better behavior than always making them blue (boring).

Test Plan:
what

{F1208333}

wut

Reviewers: hach-que, chad

Reviewed By: chad

Maniphest Tasks: T10737

Differential Revision: https://secure.phabricator.com/D15643