Default node network group deleted successfully

[Julia Aranovich]

DELETE request on default node network group completes successfully, node network group with is_default == True attribute can be deleted without any exception.

Also, It is possible to delete the last node network group in cluster.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/262213

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/262213
Committed: https://git.openstack.org/cgit/openstack/fuel-web/commit/?id=b5f606a26416a866f14f2a4100bd5493854b9c9c
Submitter: Jenkins
Branch: master

commit b5f606a26416a866f14f2a4100bd5493854b9c9c
Author: Artem Roma <email address hidden>
Date: Tue Dec 29 13:22:01 2015 +0200

    Add validation to delete operation for NodeGroupHandler

    What was done:
    * call to code of validator added for DELETE method of the handler;
    * removed unnecessary check from the validator
    * added tests

    Change-Id: Ie6f894773328aed743cea371f2c50707151c3ae0
    Closes-Bug: #1529591

[Dmitriy Kruglov (dkruglov)]

Please cherry pick the patch to stable/8.0 branch (if the target milestone is indeed 8.0).

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/8.0
Review: https://review.openstack.org/266270

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/266270
Committed: https://git.openstack.org/cgit/openstack/fuel-web/commit/?id=09b2cde18b842471b6cc8f600a5a0d8236324e01
Submitter: Jenkins
Branch: stable/8.0

commit 09b2cde18b842471b6cc8f600a5a0d8236324e01
Author: Artem Roma <email address hidden>
Date: Tue Dec 29 13:22:01 2015 +0200

    Add validation to delete operation for NodeGroupHandler

    What was done:
    * call to code of validator added for DELETE method of the handler;
    * removed unnecessary check from the validator
    * added tests

    Change-Id: Ie6f894773328aed743cea371f2c50707151c3ae0
    Closes-Bug: #1529591
    (cherry picked from commit b5f606a26416a866f14f2a4100bd5493854b9c9c)

[Veronica Krayneva (vkrayneva)]

Verified on #478 iso

[Mikhail Samoylov (msamoylov)]

Passed in mos-402 ISO
Steps:
1. Create cluster
2. Try to delete from fuel-cli default node group

Actual result the same that expected
[root@nailgun ~]# fuel nodegroup --env 2 --group 2 --delete
Default node groups cannot be deleted.