Fix transposed name/email in Mailgun adapter

Summary: Ref T12677. This argument order was swapped.

Test Plan: Will push/verify.

Maniphest Tasks: T12677

Differential Revision: https://secure.phabricator.com/D19042

src/applications/metamta/adapter/PhabricatorMailImplementationMailgunAdapter.php

@@ -21,7 +21,7 @@ final class PhabricatorMailImplementationMailgunAdapter
     if (empty($this->params['reply-to'])) {
       $this->params['reply-to'] = array();
     }
-    $this->params['reply-to'][] = $this->renderAddress($name, $email);
+    $this->params['reply-to'][] = $this->renderAddress($email, $name);
     return $this;
   }