What's Changed
* cleanup: Improve style, formatting; use flake8, isort by EliahKagan in https://github.com/cwacek/python-jsonschema-objects/pull/254
* bugfix: Fix 218 by serializing "null" for "null" types by cwacek in https://github.com/cwacek/python-jsonschema-objects/pull/263
**Full Changelog**: https://github.com/cwacek/python-jsonschema-objects/compare/0.4.5...0.4.6