Python 3 Support

[leotada]

This needs a Python 3 support. I can help.

[leotada]

I done this here: https://github.com/leotada/koparka/tree/py3

[wezu]

I will accept pull requests, but please make sure it will still work on py2. So I'd rather see basestring defined as basestring=str on py3 then just replacing basestring with str. I'm also not 100% sure how py2 likes explicit relative imports - I've seen 2to3 add leading dots to the imports in demo.py, but demo.py is not part of a package, you should not import it, just run it, so I don't think the relative imports are needed here.

[leotada]

https://github.com/wezu/koparka/pull/14

[wezu]

It looks good, I don't see anything that should make problems, but I admit I haven't yet tested it on py 2.7 and py 3.6.