This patchset implements Neutron rolling upgrade logic as described
in [1].

Due to only neutron, vpnass and fwaas have supported for rolling upgrade
database migration, so I used the list "neutron_rolling_upgrade_services"
in neutron/default/main.yml for contain there services.

[1] https://docs.openstack.org/neutron/latest/contributor/internals/upgrade.html

Co-author: Ha Manh Dong <donghm@vn.fujitsu.com>
Change-Id: I2ed2f941d30d4df0d0f42c0d10e7ca03ec1c166a
Implements: blueprint apply-service-upgrade-procedure