update Piwik to version 2.16 (fixes #91)

www/analytics/plugins/ImageGraph/Controller.php

@@ -1,6 +1,6 @@
 <?php
 /**
- * Piwik - Open source web analytics
+ * Piwik - free/libre analytics platform
  *
  * @link http://piwik.org
  * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
@@ -16,7 +16,10 @@ use Piwik\View;
 
 class Controller extends \Piwik\Plugin\Controller
 {
-    // Call metadata reports, and draw the default graph for each report.
+    /**
+     * @internal For Debugging only
+     * Call metadata reports and draw the default graph for each report.
+     */
     public function index()
     {
         Piwik::checkUserHasSomeAdminAccess();