Handle case in which a user has no public repos
Disable urllib3 warnings when running tests

See [1] for more information.

  [1] https://urllib3.readthedocs.org/en/latest/security.html
Print errors directly to stderr

...bypassing the logger. It was a bit crazy to use the logger for this.

I'll need to figure out how to do this in a Python 3-compliant way,
though.
Use Python 3-compatible print function
setup.py: PyPI classifiers