Variable response from request data

Hi,

I’ve added the ability to get variable responses from an endpoint, based on request data. This is something I personally need from canned. I usually end up needing this when working with anything more than a simple api.  

Please feel free to close if it doesn’t fit with the goals of the project. 

Thanks.
Do you mind fixing the formatting? The other parts of the readme are formatted with 80chars per line, I can do it as well post merge but want to keep the Readme "clean"