Inconsistent HTTP error code for validation

[Nachi Ueno]

IP address or Mac validation failures return 422
Otherwise quantum returns 400.

This is not consistent.
We should have consistent error code handling.

[dan wendlandt (danwent)]

I thought we had found and removed all 422's a long time ago, but looks like some remain from the original v2 implementation. I think it makes sense to remove these. Seems low risk.

[Salvatore Orlando (salvatore-orlando)]

I think there are 422 thrown also in other cases (for instance if you do a PUT on a post-only attribute).

Please keep in mind that if this will not land in Folsom, changing it in Grizzly will produce a non compatible API change, so it is "relatively" low risk.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/12666

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/12666
Committed: http://github.com/openstack/quantum/commit/255552cb7bf4dd5849791a7c88cda709f6ce829d
Submitter: Jenkins
Branch: master

commit 255552cb7bf4dd5849791a7c88cda709f6ce829d
Author: Nachi Ueno <email address hidden>
Date: Sun Sep 9 04:58:07 2012 +0000

    Change 422 error to 400 error

    Fixes bug 1046956
    For error code consistency, change 422 error to 400 error

    Change-Id: I1d150c883e204af8a32de61f91392a46d8397ae1