add composer's vendor directory

vendor/symfony/yaml/Exception/DumpException.php

@@ -0,0 +1,21 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Yaml\Exception;
+
+/**
+ * Exception class thrown when an error occurs during dumping.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class DumpException extends RuntimeException
+{
+}