Add new live_migration case to support block_migration=auto

Compute microversion 2.25 supports auto block_migration
and also the disk_over_commit flag has been removed.

Details: http://docs.openstack.org/developer/nova/api_microversion_history.html#maximum-in-mitaka

This commit adds tests for the same.
Also adds the below required schema for version 2.25 tests.

- 2.3 Schema. Details:
http://docs.openstack.org/developer/nova/api_microversion_history.html#maximum-in-kilo

- 2.16 Schema. Details:
http://docs.openstack.org/developer/nova/api_microversion_history.html#id14

- 2.23 Schema. Details:
http://docs.openstack.org/developer/nova/api_microversion_history.html#id21

Co-Authored-By: ghanshyam <ghanshyam.mann@nectechnologies.in>

Change-Id: I0fb5567cb4f7363465b68b86174b2df039f183d9
12 files changed