Allows to get a string representation for the XmlRpcMethodValue inside the given XmlRpcMethodResponse.
The string returned must be not deallocated. This is already done while calling to vortex_xml_rpc_method_response_free.
This function can only be called if the method response object status is XML_RPC_OK.
|response ||The method response to get its internal value as an string.|
- The string internal representation or NULL if the incoming XmlRpcMethodResponse status is not XML_RPC_OK.