Python 3.x Compatibility

[coxley]

While I would love to have this Python 3.5 compatible, probably more feasible to make 2.7 and 3.3 compatible. From what I understand 3.3 is one of the easier py3 versions to maintain forward and backward projects.

We should use six sparingly and when needed to do conditional version blocks, treat py2 as the special case:

if six.PY2:
  # Special code
else:
  # Modern code

This way it allows py4 when released to fall back to py3 code which will probably be compatible.

[jathanism]

I think this is a great idea after we launch v1.0