Removed form_field attributes.
Added extra fields for HTML rendering like label and help text.
Added fields for sorting and grouping. Removed old collection system.
Added config groups to config view via OPTIONS requests.
Regrouped all variables.
Added validation. Changed internal handling.
Refactored user creation and update via REST API. Used new serializer.
Cleaned up management commands, signals and imports. Moved code from 'api.py' to 'models.py'.
Changed usage of group 'Registered'. Now the users don't have to be members to gain its permissions. Used customized auth backend for this.
Added and changed some tests.
