Add missing use statements

Author: fabpot

Firewall.php

@@ -17,6 +17,7 @@
 use Symfony\Component\HttpKernel\Event\GetResponseEvent;
 use Symfony\Component\HttpKernel\Event\RequestEvent;
 use Symfony\Component\HttpKernel\KernelEvents;
+use Symfony\Component\Security\Http\Firewall\AbstractListener;
 use Symfony\Component\Security\Http\Firewall\AccessListener;
 use Symfony\Component\Security\Http\Firewall\LogoutListener;