Convert PHUIObjectBoxView to AphrontTagView

Summary: Attempting to clean PHUIObjectBoxView up a little as well as finally being able to addClass on the sucker. I'm running into some issue with addTabs though, which on Files isn't firing.

Test Plan: Bounce around tons of screens.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D15291