openstack/networking-bgpvpn - networking-bgpvpn - OpenDev: Free Software Needs Free Tools

This repo is now testing only with Python 3, so let's make
a few cleanups:
- Remove python 2.7 stanza from setup.py
- Remove obsolete sections from setup.cfg
- Update classifiers
- Update requirements, no need for python_version anymore
- Use newer openstackdocstheme and Sphinx versions
- Cleanup */source/conf.py to remove now obsolete content.
- Add pytest as test-requirement, horizon needs this now
 for calling horizon tests
- Add mock as test-requirement, this repo needs mock and
 did not declare it.
Change-Id: I402053fb4e41d91d19005f2c1c070af2918d0ceb

Change-Id: I71d77ba689ddebfb060aab48466ab7b6612f9591

Change-Id: Ibbc0c1f767cfcc5f088a2e3fa446ba8462330bdc

Change-Id: I350158fb9fb6c765b2c267fb9393292fb42b5cb0

Change-Id: I071b6feffb5843b6aa5fd85fba8b4f385812144d