Added tests for RemoteSignedCertificate
Added tests for RemoteSignedCertificate

Signed-off-by: Diogo Monica <af59d16c17418a87a14256b5c4cf5603534cee14@gmail.com>

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