[Security/Core] added missing method to interface

src/Symfony/Component/Security/Core/Authentication/RememberMe/PersistentTokenInterface.php

@@ -19,6 +19,12 @@ namespace Symfony\Component\Security\Core\Authentication\RememberMe;
  */
 interface PersistentTokenInterface
 {
+    /**
+     * Returns the class of the user
+     * @return string
+     */
+    function getClass();
+
     /**
      * Returns the username
      * @return string