Unable to create domain if name ends with another domain ending

[Pavel Kirpichyov]

Steps to reproduce:
1) Create domain example.com in tenant A
2) Create domain ample.com in tenant B
3) 403 error, because exception will be thrown:
Unable to create domain because another tenant owns a subdomain of the domain

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/158693

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/158693
Committed: https://git.openstack.org/cgit/openstack/designate/commit/?id=c09750420ca00ebaafe54107fb2c952a48b45d2b
Submitter: Jenkins
Branch: master

commit c09750420ca00ebaafe54107fb2c952a48b45d2b
Author: Graham Hayes <email address hidden>
Date: Tue Feb 24 13:55:43 2015 +0000

    Fixed _is_superdomain check in central

    Previously this search term would match on the domain test so that
    t.zone.fqdn. would be marked as a super domain of test.zone.fqdn.

    This ensures the check only matches true super domains

    Change-Id: I9e2b28b6dfbe7e1822b4ba5f96f96d2bb15ea248
    Closes-Bug: 1423148