Add tox support

This adds support for tox to create a virtual environment for all
development.  You can invoke it by making sure tox is installed:

   $ pip install tox

Then running:

   $ tox

from the local directory.

Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>
Make flake8 more happier

Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>