Jump to Symfony 3.4

Thanks to the BC compatibility, almost nothing have to be changed.
All changes are related to new bundle version of:
- SensioFrameworkExtraBundle
- DoctrineFixturesBundle

src/Wallabag/CoreBundle/Controller/ExportController.php

@@ -2,10 +2,10 @@
 
 namespace Wallabag\CoreBundle\Controller;
 
-use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
 use Symfony\Bundle\FrameworkBundle\Controller\Controller;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+use Symfony\Component\Routing\Annotation\Route;
 use Wallabag\CoreBundle\Entity\Entry;
 
 /**