Offer the possibility to define version compatibility from plugins

app/Core/Plugin/PluginException.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace Kanboard\Core\Plugin;
+
+use Exception;
+
+/**
+ * Class PluginException
+ *
+ * @package Kanboard\Core\Plugin
+ * @author  Frederic Guillot
+ */
+class PluginException extends Exception
+{
+}