Add new service level classes

Since Pike default ceilometer backend is gnocchi and database publishers
are deprecated, this commit create classes for ceilometer non-database
setup. This will allow to smoothly switch to Gnocchi as publisher. Also
if publisher isn't set in pillar, default publisher notifier will be used.

Change-Id: I78cf9e12591c474738c0bc14b1c1777974e876e0
Related-Prod: https://mirantis.jira.com/browse/PROD-20813
14 files changed