Add Glyphicons Halflings Font and Examples

Summary: This adds in the Glyphicons Halflings Font/Iconset as an option for PHUIIconView along with a standard set of 10 colors. This will be a replacement for the standard action icon set in upcoming diffs, as well as obviously give us more flexibility, less KB, and less design resource time managing images.

Test Plan: UIExamples, Diviner

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D8798