To pass custom data in query parameter

There is a query option in flow.js object, and it sends it's contents to php in params member of the Request object. BUT! it is not accessible in client code. This PR makes it possible to access custom params specified in client part in the query option.

Author: olegabr

src/Flow/Request.php

@@ -45,7 +45,7 @@ public function __construct($params = null, $file = null)
      *
      * @return string|int|null
      */
-    protected function getParam($name)
+    public function getParam($name)
     {
         return isset($this->params[$name]) ? $this->params[$name] : null;
     }