mTLS between service-discovery-controller and NATS
mTLS between service-discovery-controller and NATS

This commit enables mTLS between service-discovery-controller and NATS.
Only the client auth has to be specified in YAML; the NATS CA gets into
service-discovery-controller via the nats-tls BOSH link.

cloudfoundry/cf-deployment,cloudfoundry/cf-deployment