A user authentication and authorisation framework plugin for Dancer2 apps.

Makes it easy to require a user to be logged in to access certain
routes, provides role-based access control, and supports various
authentication methods/sources (config file, database, Unix system
users, etc).

Designed to support multiple authentication realms and to be as
extensible as possible, and to make secure password handling easy (the
base class for auth providers makes handling `RFC2307'-style hashed
passwords really simple, so you have no excuse for storing plain-text
passwords).