added plugin screen (#671)

src/Plugin/PluginInterface.php

@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Plugin;
+
+interface PluginInterface
+{
+    /**
+     * @return string
+     */
+    public function getName();
+
+    /**
+     * @return string
+     */
+    public function getPath();
+}