Add notifications for identity CRUD events

This patch adds support for notifications for the following
resources:

  user, group, project, role, trust

on the following events:

  create, delete, update

For more information on what events keystone supports visit:
http://docs.openstack.org/developer/keystone/event_notifications.html

Change-Id: I4ff07803537daf6937fba02e9ae8fe2afec938e5
Sahara integration with Ceilometer

Added ability for Ceilometer to parse notifications from Sahara

Partially implement: blueprint ceilometer-integration

Change-Id: I8845500082a6a6892fb1e714c75884a7dd9fff02
Merge "Sahara integration with Ceilometer"
Merge "Add notifications for identity CRUD events"