Federation (#61)
* Fix CORS header spelling
* Temprarily disable an unreliable test due to bad test setup
* Federation: Implemented Code Flow
* Federation: External User Generation
* Plugin system rewrite
* Federation Integration
* Clients are now loaded via the Plugin API
* YAML is now the default user backend
* Better test setup
* All persistent state is now stored in either /keys or /config
* Removed `import_certfile` option.
This is now possible thanks to a much simpler saving location of /keys/<client_id>.cert
* Automated Setup with Plugins
* Plugin for persistent storage
Uses Postgres
Configuration Defaults are now part of Omejdn
* Plugin Documentation
* Rubocop
* Update Gemfile
* SIOP Implementers Draft Support
* Add missing audience check
* Better internal user selection handling
* Refactoring
* UI improvements
* Per-user consent
* Federation Fixes
* Federation Plugin Documentation
* Self-contained Federation Plugin
* Plugin System: Flow Events
