setup.cfg: Add universal wheel configuration.
README.rst: Make pure ReStructuredText.

The previous version had some sphinxisms in it.  This may have
been the cause for the PyPI text not being recognized as ReST
on pypi.python.org.
Add support for --install-test-requirements
gitignore: Add *.egg.

I have no clue how I didn't add this already.
Add support for --install-extra-requirements
Travis CI: Remove branches section.

This may be causing builds to be skipped.  Gleaned from
https://github.com/travis-ci/travis-ci/issues/2498.
Merge pull request #6 from dave-shawley/support-installation-kwds

Support installation kwds