Improve server functional tests
Improve server functional tests

Patch set [1] fixed timing issues related to the server functional
tests. As part of the review, additional enhancements were
suggested. This patch set provides those enhancements. In particular,
the functional tests will now check for the cirros256 flavor and
the cirros-*-uec image.

[1] https://review.openstack.org/#/c/313870/

Change-Id: I7fe18e26b3d09db92bbe669ffafcd16618cae383

dtroyer/python-openstackclient,openstack/python-openstackclient,dtroyer/python-openstackclient,openstack/python-openstackclient