Python 2/3 changes.
Merge pull request #19 from vinnyrose/python3

Python 2/3 changes.
Mention contributions by other AUTHORS

Thanks @floppya, @BertrandBordage, @borgstrom, @vinnyrose and @mvdwaeter!
Enforce Python 3 compatible dependencies
Version bump for Python 3 support
cleanup future imports, take six from future.utils too.