Added a red notification thunderbolt for when we're on an admin page.

Summary: The blue thunderbolt looked out of place on the red admin pages; now it matches the colors from the admin Phabricator logo.

Test Plan: Go to an admin page, see a red thunderbolt.  Go to a not-admin page, see a blue thunderbolt.

Reviewers: epriestley

CC: aran, Korvin

Maniphest Tasks: T1427

Differential Revision: https://secure.phabricator.com/D2895

webroot/rsrc/css/application/base/standard-page-view.css

@@ -251,6 +251,10 @@ a.handle-disabled {
   width: 60px;
 }
 
+.phabricator-admin-page-view .icon-menu-notifications {
+  background: url(/rsrc/image/notification_menu_admin.png);
+}
+
 .icon-menu-notifications {
   background: url(/rsrc/image/notification_menu.png);
 }