Converted to run on Python 3 - all tests passing
Update imagesize functionality to work with Python 3.
Update sanitizer.

Cleanup and the xhtml serializer functionality if being removed.
Update to match the new sanitizer.
Remove sanitize doctest.

It's fully covered in the other tests, and this simplifies trying to bring Python 2.7 and 3 code in line.
Fix a test on Python 2.7

The encode is extraneous on Python 3.
Remove unused import from tests.
Unicode raw tests now pass for both python 2.7 and 3.3
Cleaning up warnings about unused modules.
More general cleanup.