fix header comments

src/Silex/GetResponseForErrorEvent.php

 <?php
 
 /*
- * This file is part of the Symfony package.
+ * This file is part of the Silex framework.
  *
  * (c) Fabien Potencier <fabien@symfony.com>
  *

src/Silex/SilexEvents.php

 <?php
 
 /*
- * This file is part of the Symfony framework.
+ * This file is part of the Silex framework.
  *
  * (c) Fabien Potencier <fabien@symfony.com>
  *
- * This source file is subject to the MIT license that is bundled
- * with this source code in the file LICENSE.
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
  */
 
 namespace Silex;