Aggregate api should limit user to update its availability zone in metadata when its host list isn't empty

[David Jia]

Only single availability zone is supported in current Openstack design, we should limit users to modify aggregate's , whose host list isn't empty, availability zone in metadata to aviod user's wrong operation and confusion.

Here is the bug for adding limitation in aggregate-add-host api:https://bugs.launchpad.net/nova/+bug/1196893, it will limit user to add multi availability zone for a host

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/36786

[David Jia (jiataotj)]

According to code review comments and discussion, aggregate's multi az issue can be fixing in bug #1196893, but we shouldn't limit user to add host into aggregate has az and aggregates without az, because it work as design, so I'll use this bug to add non az support into fixing for bug #1196893.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/36786
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=734d9a70f81891c793e20aa23ea0ec0e5fda12b7
Submitter: Jenkins
Branch: master

commit 734d9a70f81891c793e20aa23ea0ec0e5fda12b7
Author: jiataotj <email address hidden>
Date: Fri Jul 12 14:40:31 2013 +0800

    Fix multi availability zone issue part 2

    In order to keep consistency with fixing in
    code review:
    I788782a9f21ec2672551f75123753175bb268586

    adding aggregate az checking logic to guarantee
    that aggregate updating and aggregate metadata
    updating shouldn't be done when aggregate's hosts
    belong to other az. So, when az conflict exist,
    user should remove those hosts.

    sync the changes into V3 aggregate APIs.

    Fixes: bug #1200479
    Change-Id: I18ad1ac22c6aee298ccc75c978b85241ae1ac616