Fix mpdf relative url's and logging

Relative url's weren't supported, because mpdf was trying to get it by
hostname in the request. If however a proxy should update the hostname
it wouldn't work. Therefore the `base` html tag was added which was
supported by mpdf for resolving absolute urls. Also the
logging was added and decent symfony shutdown.

app/Resources/views/base.html.twig

@@ -13,6 +13,9 @@
     <link href="{{ asset_url }}" type="text/css" rel="stylesheet" media="screen, print" />
     {% endstylesheets %}
 {% endblock head_style %}
+{% block head_bottom %}
+    <base href="{{ app.request.schemeAndHttpHost ~ app.request.baseUrl }}">
+{% endblock head_bottom %}
 
 {% block navbar %}
     {#{{ mopa_bootstrap_navbar('frontendNavbar') }}#}

src/Surfnet/StepupSelfService/SelfServiceBundle/Controller/RegistrationController.php

@@ -26,6 +26,7 @@
 use Surfnet\StepupSelfService\SelfServiceBundle\Value\AvailableTokenCollection;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpFoundation\ResponseHeaderBag;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 
 class RegistrationController extends Controller
@@ -178,9 +179,25 @@ public function registrationPdfAction($secondFactorId)
                 'tempDir' => sys_get_temp_dir(),
             )
         );
+        $mpdf->setLogger($this->get('logger'));
+
         $mpdf->WriteHTML($content);
-        $mpdf->Output('registration-code.pdf', MpdfDestination::DOWNLOAD);
+        $output = $mpdf->Output('registration-code.pdf', MpdfDestination::STRING_RETURN);
+
+        $response = new Response($output);
+        $response->headers->makeDisposition(
+            ResponseHeaderBag::DISPOSITION_ATTACHMENT,
+            'registration-code.pdf'
+        );
+
+        $response->headers->set('Content-Description', 'File Transfer');
+        $response->headers->set('Content-Transfer-Encoding', 'binary');
+        $response->headers->set('Cache-Control', 'public, must-revalidate, max-age=0');
+        $response->headers->set('Pragma', 'public');
+        $response->headers->set('Expires', 'Sat, 26 Jul 1997 05:00:00 GMT');
+        $response->headers->set('Last-Modified', '' . gmdate('D, d M Y H:i:s') . ' GMT');
+        $response->headers->set('Content-Type', 'application/pdf');
 
-        exit;
+        return $response;
     }
 }