Added fix for doubled parameters

As explained in #343 it is not possible to have same field in both the request uri and in query string or request body.

This little fix tries to solve this problem. All *doubled* fields are temporary saved and merged back to the real `params` variable after the request url has been populated.

Want to reproduce the behavior?
Create a resource which takes some route parameter `foo`. The resource could contain in the request body a field which is named equal to this route parameter. This results in a field named `foo` in the *Requirements* and a field named `foo` in the *Parameters* list.

Please do not ask why I need those parameters like this. It's a customer requirement :)

What do you think?