Run python-modernize on test suite and add unicode_literal import.
More py2/py3 compatibility.

 - Load everything internally as unicode.
 - Added utility for reraising exceptions.
More p2/p3 compatible in/output unicode handling.

 - use utilities from the `kitchen` package
 - https://pythonhosted.org/kitchen/unicode-frustrations.html
 - https://pythonhosted.org/kitchen/api-text-converters.html