OpenStack is dropping the py2.7 support in ussuri cycle. Make a few cleanups: - Remove python 2.7 stanza from setup.py - Add requires on python >= 3.6 to setup.cfg so that pypi and pip know about the requirement - Remove section from setup.cfg: Wheel is not needed for python 3 only repo - Update requirements Change-Id: Ibca03f9ebaeaca595e027be9cb5900c368c8de6dchanges/57/715457/1