Python 3.3 support

Hi Alvin,

I found your package very useful for preparing a coding competition event at the company I work for.
However I'd like to use it running on Python 3.3.
Therefore, I'm attaching my pull request with a small changes (mostly importing issues) that enable Python 3.3 support.
I also wrote some (very basic) test cases to be sure that the package still works correctly with Python 2.6+

I hope my changes looks fine for you and would be grateful for preparing a new pypi release after merging.

In case of any doubts or concerns -  let me know.

Cheers,
Rad