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
maybe add a comment that the "and f.filename" is required because werkzeug.datastructures.FileStorage is missing the __bool__ method for python 3, so we can remove this again as soon as we require a fixed werkzeug version.