[feature/php-events] Add mock for unit tests and create it were needed

PHPBB3-9550

tests/mock/event_dispatcher.php

@@ -0,0 +1,16 @@
+<?php
+/**
+*
+* @package testing
+* @copyright (c) 2012 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+class phpbb_mock_event_dispatcher
+{
+	public function trigger_event($eventName, $data)
+	{
+		return array();
+	}
+}