Adds keystone snapshot to the controller node

Snapshot 'keystone_installed' will contain the following packages

    1. keystone

This snapshot will also configure keystone as required for OpenStack.
This snapshot can be used to obtain stable running version of
controller node and can be used to revert back to this point in case
the students break the cluster.

Change-Id: I473f3970e46666bbf55d092905ed1ca740c4196d