public function feedAction($_format)
    {
        $format   = $_format == 'xml' ? 'rss' : $_format;
        $articles = $this->get('vince_cms.repository.article')->findAllPublishedIndexableOrdered();

        return $this->render(sprintf('VinceCmsBundle:Templates:feed.%s.twig', $format), array(
                'articles' => $articles,
                'id'       => sha1($this->get('router')->generate('cms_feed', array('_format' => $format), true)),
            )
        );
    }