add IntlDateFormatter for formatting locale-dependent date and time

views/html/users/index.tpl

@@ -7,7 +7,7 @@
 	<li>
 		<h2><a href="<?=$linker->link(array('user', $user['username']), 1)?>"><?=$user['username']?></a></h2>
 		<details>
-			<summary><?=_('registered on')?> <?=date(\hhu\z\Utils::DATEFORMAT, strtotime($user['created']))?></summary>
+			<summary><?=sprintf(_('registered on %s'),  $dateFormatter->format(new \DateTime($user['created'])))?></summary>
 		</details>
 	</li>
 	<?php endforeach ?>