Remove 1x AppIcons, use FontIcons instead
Summary: Removes the 1x application icons, and uses the fonticons instead. Feed was only known location.
Test Plan:
feed, dashboards, grep for use
{F275636}
Reviewers: btrahan, epriestley
Reviewed By: epriestley
Subscribers: hach-que, Korvin, epriestley
Differential Revision: https://secure.phabricator.com/D11496