Resolve the service reference before intantiating proxy for it

The original code assumed that if it has a ServiceReference, that
service does not disappear. Now it resolves it before deciding whether
to use a proxy.

Change-Id: I4dfdf886ab1f6fca7cdd523cf3e112af6d9b1411
Signed-off-by: Robert Varga <rovarga@cisco.com>