StatusPolicy#account was renamed to StatusPolicy#current_account in
upstream. This commit renames the local-only changes to match and
augments the #show? policy spec with what we expect for local-only
toots.
* 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
