update Piwik to version 2.16 (fixes #91)

www/analytics/vendor/psr/log/Psr/Log/LoggerAwareInterface.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Psr\Log;
+
+/**
+ * Describes a logger-aware instance
+ */
+interface LoggerAwareInterface
+{
+    /**
+     * Sets a logger instance on the object
+     *
+     * @param LoggerInterface $logger
+     * @return null
+     */
+    public function setLogger(LoggerInterface $logger);
+}