Add post-start option to os-svc-daemon.

We also migrate os-svc-daemon to supporting switches to modify its
behavior and be more flexible as it grows. The old positional style is
still supported but will be deprecated.

Each service will have a unique way to verify that it has started. The
default 'exec sleep 1' will be sufficient for some, but not all. Quantum
is the first example, which can take more than 5 seconds to open a
listening socket.

Due to a lack of knowledge and testing on systemd, it will simply print
out a warning about the issue until we have a better answer.

Change-Id: I8d0e0842dfa66b2e32b942270ed071e593d3865e
Make quantum-server post-start sleep 10 seconds.

A better long term solution is something that polls trying to reach
quantum-server on the port it is configured to listen on. However,
extending the usual sleep to 10 seconds has at least a moderate chance
of avoiding the race between 'start quantum-server' and the listen()
call that makes it reachable.

Change-Id: I56453e3e9d718216e3cfee0a3bc353c51f74b3be
Merge "Add post-start option to os-svc-daemon."
Merge "Make quantum-server post-start sleep 10 seconds."