Try layering state icons on PHUICircleIconView

Summary: I think this is reasonable for my current use case, but stacking icons overally is pretty clunky.

Test Plan:
UIExamples

{F4978899}

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D18032