Added Python3 support. Now Python 2 or 3 can be used with the same code

The code is runnable with Python3 and Python2 now. Tested with Python 2.7 and Python 3.3.
Please write code in the future for Python 2 and 3, so both are supported
if PY2:

(or rather check if you can't just make it work for both pythons, should be possible)