removed trailing dot to make it consistent with other validator messages

src/Symfony/Bridge/Doctrine/Validator/Constraints/UniqueEntity.php

@@ -23,7 +23,7 @@ use Symfony\Component\Validator\Exception\UnexpectedTypeException;
  */
 class UniqueEntity extends Constraint
 {
-    public $message = 'This value is already used.';
+    public $message = 'This value is already used';
     public $em = null;
     public $fields = array();