2to3 in setup

This enables the setuptools option to run 2to3 on build. 

With 2 additional small changes, this makes the test suite run in full, but fail, on python3. I get 

    Ran 876 tests in 4.114s
    
    FAILED (failures=33, errors=613, skipped=18)

Using `python3 setup.py test` to run.