Remove redundant code from magnum.test.utils

[Hua Wang]

Some codes in magnum.tests.utils is redundant. The Database class has been defined in magnum.test.unit.db.base.
get_dummy_session and create_models_from_data are not used by other codes. So we just remove it.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/203942

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/203942
Committed: https://git.openstack.org/cgit/openstack/magnum/commit/?id=cb63897e0ee5c3e179c05ba0b9191fac09ff3401
Submitter: Jenkins
Branch: master

commit cb63897e0ee5c3e179c05ba0b9191fac09ff3401
Author: Hua Wang <email address hidden>
Date: Mon Jul 13 23:50:16 2015 +0800

    Remove redundant code from magnum.test.utils

    Some codes in magnum.tests.utils is redundant. The Database class
    has been defined in magnum.test.unit.db.base. get_dummy_session
    and create_models_from_data are not used by other codes. So we
    just remove it.

    Change-Id: Ib91e1f61f0032221fe4f45237b5ea8cf09d13564
    Closes-Bug: 1476458