update Piwik to version 2.16 (fixes #91)

www/analytics/plugins/VisitFrequency/Widgets.php

@@ -0,0 +1,23 @@
+<?php
+/**
+ * Piwik - free/libre analytics platform
+ *
+ * @link http://piwik.org
+ * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
+ *
+ */
+namespace Piwik\Plugins\VisitFrequency;
+
+class Widgets extends \Piwik\Plugin\Widgets
+{
+    protected $category = 'General_Visitors';
+
+    public function init()
+    {
+        $this->addWidget('VisitFrequency_WidgetOverview', 'getSparklines');
+        $this->addWidget('VisitFrequency_WidgetGraphReturning',
+                         'getEvolutionGraph',
+                         array('columns' => array('nb_visits_returning')));
+    }
+
+}