Configure rabbitmq credentials in keystone.conf

Rabbitmq credentials in keystone.conf should be updated according
to localrc

This is done mostly to enable keystone notifications.

There are 2 cases where we can use notifications from keystone:
A) Collect audit notifications in ceilometer
B) Collect profiling data

Change-Id: I381d4d670755aa691743caa02df7dc55e05784c2
Merge "Configure rabbitmq credentials in keystone.conf"
Merge branch 'master' of https://github.com/openstack-dev/devstack