Add support for Python 2.7 and 3.4 using six

[morenosan]

Hi!

I've ported the package to support Python 3.4 using six. Installation works in 2.7 and 3.4 and tests passes in both versions.

The changes are minimal on the code but I had to change the setup.py file to install six as a dependency. Also I had to remove the execution of the tests previous to the installation because when setup.py is executed, six still is not installed. Tests can be executed with:

python setup.py test

Finally I added a README file, that is also used as the long_description field.

Hope you find it useful.