conform with PEP8

I ran [autopep8] over the code to make it conform to the [pep8] style
guidelines (4 space indent, spaces after commas etc.).

I have some other contributions to make and wanted to have some definition of
the coding style. If you'd rather stay as you are then I can just work with
that :)

[autopep8]: http://pypi.python.org/pypi/autopep8
[pep8]: https://www.python.org/dev/peps/pep-0008/