veyron/services/proxy/proxyd: Add // to the published address.
veyron/services/proxy/proxyd: Add // to the published address.

Servers that are not mounttables should published addresses that end
with // to indicate that they don't need to be resolved further.

Change-Id: If99c538fd1ad826d173c6a4878359f58e81b58b2

vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref,vanadium/go.ref