http error updates

https://pypi.python.org/pypi/fleece/0.4.2
fa42024 - 2016-05-18 - Bump fleece version - Bruce Stringer
9aceff5 - 2016-05-18 - Don't explode if provided status code isn't found - Ryan Walker
59544c5 - 2016-05-18 - Add extra status codes to HTTPError - Ryan Walker
4f9c6a8 - 2016-05-17 - Default to 401 for invalid tokens - Ryan Walker