Previously, we passed the location for our user config file to the
StyleGuide. This was intended to be a way to tell pep8's StyleGuide
to use that as a user config file, but instead that became the default
for the --config command-line option. This caused that to have higher
priority than the project configuration file.

Closes #122

We were very naively "normalizing" options parsed and provided by
setuptools. This updates our handling to store the Option instance
from optparse so we can inspect the type, action, and option name for
more intelligent option normalization.

Closes #121

https://gitlab.com/pycqa/flake8/issues/40

* Adding an ignore option in [flake8] wasn't working because pep8.StyleGuide
turned the string sent in into a tuple, which the option parser needs to receive
as an iterable that isn't a string. Split on spaces, commas, or semicolons using
re.findall in order to get a list of error/warnings to pass to StyleGuide
properly.

* Add self to contributors

(cherry picked from commit 8f8a7d458f8f46669398591bffd93462d4e439ed)

This preserves backwards compatibility in the event someone was using
EXTRA_IGNORE as it should have been used