Added the missing license header and removed the author info

Symfony policy is to *not* add the authors in test files. Personally I don't agree ... but in this repo we must follow the Symfony practices. That's why I removed you from here ... but I added you in the PHP class associated with this test.

Author: javiereguiluz

tests/AppBundle/Form/DataTransformer/TagArrayToStringTransformerTest.php

@@ -1,5 +1,14 @@
 <?php
 
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
 namespace Tests\AppBundle\Form\DataTransformer;
 
 use AppBundle\Entity\Tag;
@@ -11,8 +20,6 @@
  * Tests that tags are transformed correctly using the data transformer.
  *
  * See http://symfony.com/doc/current/testing/database.html
- *
- * @author Jonathan Boyer <[email protected]>
  */
 class TagArrayToStringTransformerTest extends \PHPUnit\Framework\TestCase
 {