Remove extraneous __init__.py content
Added docstring
Simplification of pep8 setuptools command, almost qualifies
as a total re-write.

Minor test updates since the new impl exits with pep8's exit
code rather than always exit(0). This improves integration with
some build systems.

Enables full pass-thru of command line option parsing to
pep8. All pep8 cmdline options are now supported.

Non-backwards compatible changes to command line /
config file parsing, specifically the:

  --pep8-output and --check-dirs

Options are now gone. Replace --pep8-output usage with
simple shell redirection.

Replace check-dirs usage with PEP8's --exclude option.
Version bump
Minor reformatting
Break out requirements to requirements.txt
Update NEWS ahead of release
Updated readme
Fix rst syntax
Merge branch 'refactor-pep8-command-runner'