Patching and rollback should update/downgrade nodes one by one

[Vladimir Kuklin]

In order to allow user to stop patching or rollback process, we need to disable parallel deployment in deployment serializers. Along with fix for https://launchpad.net/bugs/1364343 it should check for previous environment's version. If it is not null - disable any parallel deployment stuff.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/119033

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/119033
Committed: https://git.openstack.org/cgit/stackforge/fuel-web/commit/?id=2d23d9aedbd4ea30b32f154ed5358c6890e4bf37
Submitter: Jenkins
Branch: master

commit 2d23d9aedbd4ea30b32f154ed5358c6890e4bf37
Author: Igor Kalnitsky <email address hidden>
Date: Thu Sep 4 14:10:17 2014 +0300

    Add priority serializers for different modes

    The commit introduce a new being - priority serializer. We need such
    being since we should use different priority strategies for different
    cases.

    For example:

    * We should deploy secondary controllers one-by-one in 5.0.x clusters.
    * We should deploy all nodes one-by-one in case of patching.

    Closes-Bug: #1364532
    Change-Id: I77a445a51576b59aa188128047780af4db804312

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/119371

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/119371
Committed: https://git.openstack.org/cgit/stackforge/fuel-web/commit/?id=7683df5722975c1cae48a1a3efdad872b4aaace6
Submitter: Jenkins
Branch: master

commit 7683df5722975c1cae48a1a3efdad872b4aaace6
Author: Aleksey Kasatkin <email address hidden>
Date: Fri Sep 5 16:11:40 2014 +0300

    Get rid of mess with 'cls' and 'self' in deployment serializer

    Based on comments in
    https://review.openstack.org/#/c/119033/4/nailgun/nailgun/orchestrator/deployment_serializers.py

    Changed 'cls' to 'self'

    Related-Bug: #1364532

    Change-Id: I33b90431668f3255abb7b1f33949a8f3e61f35fe