fleetctl: add an option -replace to the start command
fleetctl: add an option -replace to the start command

coreos/fleet,dongsupark/fleet,coreos/fleet,endocode/fleet,endocode/fleet,jonboulle/fleet,dongsupark/fleet,jonboulle/fleet,jonboulle/fleet,giantswarm/fleet,endocode/fleet,dalbani/fleet,giantswarm/fleet,dongsupark/fleet,coreos/fleet,dalbani/fleet,dalbani/fleet,giantswarm/fleet