Optional body class for dust background.

Summary: This adds an option dust background for certain application designs, like Macro and Pholio to help make the list views pop more.

Test Plan: Reviewed Macro and Pholio.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5209

src/applications/macro/controller/PhabricatorMacroListController.php

@@ -160,6 +160,7 @@ final class PhabricatorMacroListController
       array(
         'device' => true,
         'title' => pht('Image Macros'),
+        'dust' => true,
       ));
   }
 }