Falcon-jwt-guard

This release includes the ability to pass a `user_loader` function on Guard initialization. It accepts claims as a parameter. It's return is set to `req.context.user`.

Coverage has reached past 90% and basic functionality has been confirmed. While we will release to PyPI at this time, **this is still a "pre-release".**

When the API is finished, we will bump it to 0.1 where we will sit and experiment for a while.

Looking forward to hearing feedback and ideas for improvement.