Default application search to the topmost filter

Summary: Allow users to set a default by dragging it to the top. When they land on a page without a saved query, choose their default.

Test Plan: Hit `/paste/`, got my default results, etc.

Reviewers: chad

Reviewed By: chad

CC: aran

Differential Revision: https://secure.phabricator.com/D6140

src/applications/files/controller/PhabricatorFileListController.php

@@ -10,7 +10,7 @@ final class PhabricatorFileListController extends PhabricatorFileController
   }
 
   public function willProcessRequest(array $data) {
-    $this->key = idx($data, 'key', 'authored');
+    $this->key = idx($data, 'key');
   }
 
   public function processRequest() {