Upgrade the common setup code to the latest versions, and use setuptools-git
for sdist tarball generation.
Change-Id: I81eca9199b7d330ef8ec80482565a75f8475a78c
Additionally, remove the pep8 dep override in tox.ini so the dep we
set in tools/test-requires is actually used
Change-Id: Iceb6d7a5dd8eceeebc1408e8a5edfabb48462d3e