Adopt oslotest in DietTestCase

[Ihar Hrachyshka]

This will allow us to stay more in line with other projects in how we handle tests, and kill some code from the base test classes that duplicates what's already available in oslotest.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/264158

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/264158
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=7a2824afc46342a8cef1937384b1475e68862b27
Submitter: Jenkins
Branch: master

commit 7a2824afc46342a8cef1937384b1475e68862b27
Author: Ihar Hrachyshka <email address hidden>
Date: Wed Jan 6 13:54:00 2016 +0100

    Adopt oslotest BaseTestCase as a base class for DietTestCase

    This will make us more in line with other projects in terms of testing
    API. It also allows to remove some duplicate code from base test classes
    for Neutron, leaving just Neutron specific fixture setup there.

    Note: we don't add a new dependency because the library is already used
    in some of database functional tests through oslo.db base test classes.

    Change-Id: Ifec6cce386d8b024605496026c8469200f3c002b
    Closes-Bug: #1531484

[Thierry Carrez (ttx)]

This issue was fixed in the openstack/neutron 8.0.0.0b2 development milestone.