ref(user-data.sample): configure fleet without overwriting unit file
ref(user-data.sample): configure fleet without overwriting unit file

We can configure the fleet public_ip with cloud-config, so let's do that
without overwriting the default unit.

pierreozoux/guides,pessoa/guides,sjackman/coreos-vagrant,quantum/coreos-vagrant,kcyeu/coreos-vagrant,kikkomep/guides,kikkomep/guides,ianblenke/coreos-vagrant-kitchen-sink,j0rdn/coreos-rancher-vagrant,somespider/vm,rotespferd/coreos-vagrant,fgbreel/coreos-vagrant-kitchen-sink,pierreozoux/guides,chourobin/weave-demos,ianblenke/coreos-vagrant-kitchen-sink,pierreozoux/guides,kcyeu/coreos-vagrant,kikkomep/guides,kikkomep/guides,pierreozoux/guides,pessoa/guides,kikkomep/guides,triple-i/coreos-vagrant,errordeveloper/weave-demos,lukebond/etcd-vagrant,chourobin/weave-demos,monkey-H/nap-vagrant,2yoshi/docker-test,pdxjohnny/coreos-vagrant,cornelius-keller/coreos-vagrant-tinc,triple-i/coreos-vagrant,pierreozoux/guides,amouat/fleet-vagrant,kikkomep/guides,kikkomep/guides,leandrocp/coreos-vagrant,pierreozoux/guides,matsubo/coreos-vagrant-docker-compose,oveits/coreos-vagrant,andrewrothstein/coreos-vagrant,chourobin/weave-demos,owlab-exp/coreos-vagrant-devel,oveits/coreos-vagrant,chourobin/weave-demos,errordeveloper/weave-demos,glevand/coreos--coreos-vagrant,errordeveloper/weave-demos,monkey-H/nap-vagrant,matsubo/coreos-vagrant-docker-compose,pierreozoux/guides,phamviet/coreos-vagrant-es-cluster,kikkomep/guides,errordeveloper/weave-demos,pierreozoux/guides,phamviet/coreos-vagrant-es-cluster,fgbreel/coreos-vagrant-kitchen-sink