update Piwik to version 2.16 (fixes #91)

www/analytics/core/Tracker/VisitInterface.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
@@ -11,13 +11,13 @@ namespace Piwik\Tracker;
 
 /**
  * Interface implemented by classes that track visit information for the Tracker.
- * 
+ *
  */
 interface VisitInterface
 {
     /**
      * Stores the object describing the current tracking request.
-     * 
+     *
      * @param Request $request
      * @return void
      */
@@ -25,7 +25,7 @@ interface VisitInterface
 
     /**
      * Tracks a visit.
-     * 
+     *
      * @return void
      */
     public function handle();