Adding / correcting the file docblock throughout the project

PHPCI/Helper/WindowsCommandExecutor.php

@@ -1,4 +1,11 @@
 <?php
+/**
+ * PHPCI - Continuous Integration for PHP
+ *
+ * @copyright    Copyright 2014, Block 8 Limited.
+ * @license      https://github.com/Block8/PHPCI/blob/master/LICENSE.md
+ * @link         https://www.phptesting.org/
+ */
 
 namespace PHPCI\Helper;