R1:99676e8e331b

Add app icons to quick menu

Summary: This adds the app icons, cleans up css Ref T3623

Test Plan: see new icons in dropdown menu

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Maniphest Tasks: T3623

Differential Revision: https://secure.phabricator.com/D8124