Use openstack.nose_plugin for tests

With this change, we get similar nosetest output as other OpenStack projects do.

Change-Id: I0f6692e4cfef04c4fdea8a7a65ad6b73468f7c44
Make more use of Swob for code cleanup

Change-Id: I580135ef7c9545eb2f69ff88b3aafcd8064b81b5
Merge "Make more use of Swob for code cleanup"
Merge "Use openstack.nose_plugin for tests"