Clarify licensing info
Rename get_token_secret() to get_derived_secret().
Switch to sha256 as default hashing algorithm.
Add custom ValueError subclasses for finer-grained error reporting.
Remove "XXX TODO" that is probably not going to get done.
Prep version 0.3.0
Bump dev version number.
Fix occasional test breakage due to badly-encoded bytes.
Fix test breakage on py3
Make DEFAULT_HASHMOD a string, for easier checking in other modules.
Prep version 0.3.1
Include information about supported python versions for pypi
Include a .travis.yml for CI