Sync 'service' module from oslo-incubator

Sync 'service' module from oslo-incubator

The service module hasn't had a sync to Cinder since November
of 2014.  There have been a number of changes, including updates
to get it using the appropriate namespace for oslo and support
for moving away from using oslo.log.  So, we need to update the
module.

Current HEAD in OSLO:
---------------------
commit e589dde0721a0a67e4030813e582afec6e70d042
Date:  Wed Feb 18 03:08:12 2015 +0000
Merge "Have a little fun with release notes"

Changes merged with this patch:
---------------------
2aacb111 - Change oslo.config to oslo_config
2fbf5065 - Remove oslo.log code and clean up versionutils API
dbca53e9 - Merge "Added graceful argument on Service.stop method"
442fc223 - Added graceful argument on Service.stop method
cf429e50 - Remove extra white space in log message

Change-Id: If78596d8779b8dd5b2fc22891d7ca21ccdabc9d6