Replace action sprite with FontAwesome

Summary: Replaces the action icons in action headers with FontAwesome

Test Plan:
- grep SPRITE_ACTIONS
- grep sprite-actions
- Replace on UIExamples
- Replace on Workboards
- Replace on Dashboards
- Replace on FeedStories

{F157840}
{F157841}

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9230

scripts/celerity/generate_sprites.php

@@ -30,7 +30,6 @@ $sheets = array(
   'remarkup' => $generator->buildRemarkupSheet(),
   'menu' => $generator->buildMenuSheet(),
   'apps' => $generator->buildAppsSheet(),
-  'actions' => $generator->buildActionsSheet(),
   'minicons' => $generator->buildMiniconsSheet(),
   'conpherence' => $generator->buildConpherenceSheet(),
   'apps-large' => $generator->buildAppsLargeSheet(),