Changed the constraint to the new one
Changed the flash message handling to use the non-deprecated api

This fixes the compatibility with symfony 2.3
Merge branch '1.3.x'

Conflicts:
	Controller/ChangePasswordController.php
	Controller/GroupController.php
	Controller/ProfileController.php
	Controller/RegistrationController.php
	Controller/ResettingController.php
	Controller/SecurityController.php
	Resources/views/layout.html.twig