Add Xcp_service.configure2, which uses cmdliner

Using the new interface is not backwards-compatible because
 * we must use "--name-of-arg" rather than "-name-of-arg", hence
   the callers (init scripts) of each package needs to be changed.
 * cmdliner requires more information about the caller, in particular
   'name', 'version' and 'doc'

The old interface still exists and should work as before. Clients can
be upgraded to the new interface one at a time.

Signed-off-by: David Scott <dave.scott@citrix.com>
Regenerate OASIS

Signed-off-by: David Scott <dave.scott@citrix.com>