Calendar event transaction should show a calendar icon in Feed

Summary: Fixes T8010, Calendar event transaction should show a calendar icon in Feed.

Test Plan: Update a Calendar event, check the Feed, transaction item should have a calendar icon in bottom left corner of the box.

Reviewers: epriestley, chad, #blessed_reviewers

Reviewed By: chad, #blessed_reviewers

Subscribers: Korvin, epriestley

Maniphest Tasks: T8010

Differential Revision: https://secure.phabricator.com/D12642

src/applications/calendar/phid/PhabricatorCalendarEventPHIDType.php

@@ -8,6 +8,10 @@ final class PhabricatorCalendarEventPHIDType extends PhabricatorPHIDType {
     return pht('Event');
   }
 
+  public function getPHIDTypeApplicationClass() {
+    return 'PhabricatorCalendarApplication';
+  }
+
   public function newObject() {
     return new PhabricatorCalendarEvent();
   }