update Piwik to version 2.16 (fixes #91)

www/analytics/vendor/piwik/cache/src/Backend/NullCache.php

@@ -0,0 +1,44 @@
+<?php
+/**
+ * Piwik - free/libre analytics platform
+ *
+ * @link http://piwik.org
+ * @license http://www.gnu.org/licenses/lgpl-3.0.html LGPL v3 or later
+ *
+ */
+namespace Piwik\Cache\Backend;
+
+use Piwik\Cache\Backend;
+
+/**
+ * Can be used in development to prevent caching. Does not cache anything.
+ */
+class NullCache implements Backend
+{
+
+    public function doFetch($id)
+    {
+        return false;
+    }
+
+    public function doContains($id)
+    {
+        return false;
+    }
+
+    public function doSave($id, $data, $lifeTime = 0)
+    {
+        return true;
+    }
+
+    public function doDelete($id)
+    {
+        return true;
+    }
+
+    public function doFlush()
+    {
+        return true;
+    }
+
+}