Add agent support for node ports
Add agent support for node ports

Signed-off-by: Jana Radhakrishnan <045898bda7d4800fe4909a9831e702ab79e266be@docker.com>

fate-grand-order/swarmkit,sungwonh/swarmkit,elifa/swarmkit,dperny/swarmkit-1,cezarsa/swarmkit,Noyan759/swarmkit,jlhawn/swarmkit,aaronlehmann/swarmkit,yongtang/swarmkit,runshenzhu/swarmkit,fate-grand-order/swarmkit,RenaudWasTaken/swarmkit,dperny/swarmkit-1,AliyunContainerService/swarmkit,yp-engineering/swarmkit,RenaudWasTaken/swarmkit,docker/swarmkit,runshenzhu/swarmkit,yongtang/swarmkit,alyyousuf7/swarmkit,allencloud/swarmkit,diogomonica/swarmkit,jlhawn/swarmkit,cheyang/swarmkit,allencloud/swarmkit,vasil-yordanov/swarmkit,vasil-yordanov/swarmkit,elifa/swarmkit,deljuven/swarmkit,cezarsa/swarmkit,yp-engineering/swarmkit,aaronlehmann/swarmkit,alyyousuf7/swarmkit,cheyang/swarmkit,AliyunContainerService/swarmkit,sungwonh/swarmkit,diogomonica/swarmkit,Noyan759/swarmkit,docker/swarmkit,deljuven/swarmkit