[sombrero] add service discovery to upgrade
[sombrero] add service discovery to upgrade

Signed-off-by: Christian Ang <15ae83feccf4d84083a62aba1cdf46bd8ce2e33b@pivotal.io>

cloudfoundry-incubator/cf-networking-release,cloudfoundry-incubator/cf-networking-release,cloudfoundry-incubator/cf-networking-release,cloudfoundry-incubator/cf-networking-release