Change test-requirements.txt ajkavanagh to openstack
Change test-requirements.txt ajkavanagh to openstack

Changed from:
git+https://.../ajkavanagh/charms.openstack.git#egg=charms-openstack
to:
git+https://.../openstack/charms.openstack.git#egg=charms-openstack

This is because the tests should come from the openstack master branch.

ajkavanagh/charm-barbican,ajkavanagh/charm-barbican