code styles: header_comment and ordered_imports (#175)

src/Entity/UserPreference.php

@@ -1,5 +1,12 @@
 <?php
 
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
 namespace App\Entity;
 
 use Doctrine\ORM\Mapping as ORM;