* Add customizable user roles

* Various fixes and improvements

* Add migration for old settings and fix tootctl role management

* Add ability to purge undeliverable domains from admin interface

* Add tests

* Add moderator role and add pundit policies for admin actions

* Add rake task for turning user into mod and revoking it again

* Fix handling of unauthorized exception

* Deliver new report e-mails to staff, not just admins

* Add promote/demote to admin UI, hide some actions conditionally

* Fix unused i18n