* Allow moderators to disable/enable login
* Instead of rejecting login, show forbidden error when login disabled
Avoid confusion because when login is rejected, the message is that
the account is not activated, which is wrong.
* Fix tests
* Admin: Show unconfirmed email address on account page
* Admin: Allow staff to change user email addresses
* ActionLog: On change_email, log current email address and new unconfirmed email address
* 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
