Make reject, accept outline icons

Summary: These are a little easier on the eyes.

Test Plan:
Reject an epriestley diff.

{F146851}

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D8841

src/applications/differential/storage/DifferentialTransaction.php

@@ -353,9 +353,9 @@ final class DifferentialTransaction extends PhabricatorApplicationTransaction {
           case DifferentialAction::ACTION_CLOSE:
             return 'fa-check';
           case DifferentialAction::ACTION_ACCEPT:
-            return 'fa-check-circle';
+            return 'fa-check-circle-o';
           case DifferentialAction::ACTION_REJECT:
-            return 'fa-times-circle';
+            return 'fa-times-circle-o';
           case DifferentialAction::ACTION_ABANDON:
             return 'fa-plane';
           case DifferentialAction::ACTION_RETHINK: