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
I think I found it:
The werkzeug.datastrutures.FileStorage behaves different for Python2 and Python 3.
It implements a __nonzero__(line 2600) method, that checks if the filename is not empty. For Python 3 the method should be named __bool__, __nonzero__ is not recognized in Python 3, so bool(file) returns True, even if the filename is empty.
I think this is a bug. Do you think it should be reported? I'll write a workaround for this case...