Sync service.py from oslo-incubator with deps

devstack/unstack.sh doesn't currently work for the conductor
and api processes because they aren't handling KILL properly.
This is due to oslo bug 1263122. This commit syncs the fix for
that bug (with dependency on systemd.py).

Changes:

service.py
----------
5f12bba Implement stop method in ProcessLauncher
f718e40 Remove duplicated "caught" message
356ecd4 Move notification point to a better place
e2634a7 Add missing _LI for LOG.info in service module
53e1214 notify calling process we are ready to serve
a6fec43 Reap child processes gracefully if greenlet thread gets killed
fcf517d Update oslo log messages with translation domains
1e70078 Revert "service: replace eventlet event by threading"
0644073 Simplify launch method
8b2b0b7 Use hacking import_exceptions for gettextutils._
37e46bb disable SIGHUP restart behavior in foreground
f08f6ba service: replace eventlet event by threading
32cd4c0 Allow configurable ProcessLauncher liveness check
12bcdb7 Remove vim header
96a2d4e os._exit in _start_child may cause unexpected exception
1771a77 Adjust import order according to PEP8 imports rule
3110c0f Use multiprocessing.Event to ensure services have started
b5fba9e Move comment in service.py to correct location


systemd.py
----------
17c4e21 Fix docstring indentation in systemd
667d1ba Fixed spelling error - occured to occurred
53e1214 notify calling process we are ready to serve

Change-Id: I2005027f737fc9f81a591f1830c50cf7144cfec2
Closes-bug: 1350389
Merge "Sync service.py from oslo-incubator with deps"