sending dynamic request body to the REST API 

Hi Holger, eclipsesource,

this change enables the developer to programmatically manipulate the request body sent to the REST API. In the test example I need to use a static variable for holding the body string to be sent, which may not be in line with all junit lifecycle principles, but it makes the test development in our projects very easy and thus enables a full test coverage right from the start.

I've made this small change in my restfuse fork some time ago and have being asked about a lot,
So heres my pull request, If you put it into the master branch, we can enable more developers to find and use it,

regards
Andreas