1- Expand and migrate database in first keystone node
  2- Upgrade all nodes sequentially along with updation of each node's
     configuration file with latest release version
  3- Last keystone node, contract database

With this patch, there is small downtime when all containers are
restarted. It will be fixed in other patch.

[1] http://docs.openstack.org/developer/keystone/upgrading.html#upgrading-without-downtime



Co-Authored-By: Surya Prakash Singh <surya.singh@nectechnologies.in>
Co-Authored-By: Eduardo Gonzalez <dabarren@gmail.com>
Co-Authored-By: Duong Ha-Quang <duonghq@vn.fujitsu.com>

Partially-Implements: blueprint ks-rolling-upgrade-role

Change-Id: I2159af567c40848840ff5e483e7d1f6de760b435