There is a rollback mechanism in heat after the stack
update failed. There should be a rollback mechanism in
magnum after bay update failed.
This patch add new microversion 1.3 to add rollback
support for Magnum bay, user can enable rollback on bay
update failure by specifying microversion 1.3 in header(
{'OpenStack-API-Version': 'container-infra 1.3'}) and
passing 'rollback=True'(http://XXX/v1/bays/XXX/?rollback=True)
when issuing bay update reqeust.
Change-Id: Idd02769f98078702404a11dc9f7a3339ce4e22eb
Partially-Implements: blueprint bay-rollback-on-update-failure
63b5c21c8d