Add setup.cfg to allow universal wheel building (py2 + py3)
Add setup.cfg to allow universal wheel building (py2 + py3)

When you create a wheel file with

  ./ve/bin/python setup.py build bdist_wheel

The created wheel file is made for either python 2 or 3, depending on
your current setup. This change enables creation of a py2-py3 wheel file.

nikolas/pylti,mitodl/pylti