allow vsc-install to create correct setup.cfg's

[JensTimmerman]

the dependencies in setup.cfg for bdist_rpm sometimes need a python prefix, and sometimes don't

we should allow setting the optional prefix in setup.py's install_requires. So we don't need to maintain a separate setup.cfg when all it needs is a python prefix here and there. This way we don't need to maintain version numbers in 2 places.

[stdweird]

clusterbuildrpm does the prefixing right now. what is not working there?

[JensTimmerman]

pytz is called pytz, not python-pytz, so this breaks when clusterbuildrpm does the prefixing.

other packages include Django-Select2 (not python-django-select2)

We could add all of these as special cases in clusterbuildrpm, or have a flag in setup.py somehwere?
Or like we do now, create a setup.cfg for these