Fix for 1071: Output Formatters should be invoked for writing out the response

fixes #1071. 


<!---
@huboard:{"order":1156.5,"milestone_order":1159,"custom_state":""}
-->

Well, we do unwrap in other cases (when it is Task<T> instead of Task), we can choose to do it in this case as well. Do you want me to make that change here?