Backport Incident Updates from v3.0.0

app/Bus/Events/IncidentUpdate/IncidentUpdateEventInterface.php

@@ -0,0 +1,24 @@
+<?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\Bus\Events\IncidentUpdate;
+
+use CachetHQ\Cachet\Bus\Events\EventInterface;
+
+/**
+ * This is the incident update event interface.
+ *
+ * @author James Brooks <james@alt-three.com>
+ */
+interface IncidentUpdateEventInterface extends EventInterface
+{
+    //
+}