Audit - delete duplicate audit requests and add unique key

Summary: Fixes T1768. This is mostly a data cleanliness issue as duplicate rows don't really do anything, but let's clear it up now.

Test Plan: made some duplicate rows by adding the same auditor multiple times. ran ./bin/storage upgrade and it worked perfectly!

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T1768

Differential Revision: https://secure.phabricator.com/D10849

src/applications/repository/storage/PhabricatorRepositoryAuditRequest.php

@@ -27,6 +27,10 @@ final class PhabricatorRepositoryAuditRequest
         'auditorPHID' => array(
           'columns' => array('auditorPHID', 'auditStatus'),
         ),
+        'key_unique' => array(
+          'columns' => array('commitPHID', 'auditorPHID'),
+          'unique' => true,
+        ),
       ),
     ) + parent::getConfiguration();
   }