replace some entity shortcut by fqdn

* ChillPerson:Person
* ChillMain:Center
* ChillActivity:Activity

src/Bundle/ChillMainBundle/Test/Export/AbstractExportTest.php

@@ -83,7 +83,7 @@ abstract class AbstractExportTest extends WebTestCase
         $em = static::$kernel->getContainer()
             ->get('doctrine.orm.entity_manager');
 
-        $centers = $em->getRepository('ChillMainBundle:Center')
+        $centers = $em->getRepository(\Chill\MainBundle\Entity\Center::class)
             ->findAll();
         $circles = $em->getRepository('ChillMainBundle:Scope')
             ->findAll();