PyPI is now behind a CDN. The `--use-mirrors` option is deprecated.

See PEP 449 and https://mail.python.org/pipermail/distutils-sig/2013-May/020848.html
for more information.
Merge pull request #321 from berkerpeksag/travis-use-mirrors

PyPI is now behind a CDN. The `--use-mirrors` option is deprecated.