Support init.d-using services in os-svc-enable

os-svc-enable-upstart currently only works for Upstart scripts,
and will print a warning that the job doesn't exist, and then
create an .enable file anyway. If the action is enable, and the
Upstart config file doesn't exist, but the initscript does, run
update-rc.d.

Change-Id: Ib1e3d4e2963dd2ce4d96078781a929205c25d886
Merge "Support init.d-using services in os-svc-enable"