Finished off event interfaces

app/Events/Invite/InviteEventInterface.php

@@ -0,0 +1,19 @@
+<?php
+
+/*
+ * This file is part of Cachet.
+ *
+ * (c) Alt Three Services Limited
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace CachetHQ\Cachet\Events\Invite;
+
+use CachetHQ\Cachet\Events\EventInterface;
+
+interface InviteEventInterface extends EventInterface
+{
+    //
+}