update Piwik to version 2.16 (fixes #91)

www/analytics/plugins/PiwikPro/config/test.php

@@ -0,0 +1,13 @@
+<?php
+
+use Piwik\Tests\Framework\Mock\PiwikPro\Advertising;
+use Piwik\Plugins\PiwikPro\tests\Framework\Mock\Promo;
+
+return array(
+    'Piwik\PiwikPro\Advertising' => function () {
+        return new Advertising();
+    },
+    'Piwik\Plugins\PiwikPro\Promo' => function () {
+        return new Promo();
+    }
+);