acu93749 - Change agent to route response to request.reply_to so that ma...

...pper in control
@ryanwilliamson @tony-spataro-rs 
This change is to return control to the mapper as to where an agent sends its response to. This will help improve performance as the new router (aka broker proxy) is introduced. I verified this by changing a 5.8 instance in this fashion and then doing a reboot. I would like this change to get into 5.9.