Deprecate positional args for os-svc-daemon

We advertise supporting passthrough arguments in os-svc-daemon by using
'--' followed by extra params. This does not work if using the
undocumented old-style positional arguments and fixing this is a
non-trivial parsing problem. Lets just deprecate this old behaviour so
we can remove it.

Change-Id: I0e75f7f975325b5f199daf697004628461a20075