Add 1GB storage cap with staff bypass (#2729)

Re-applies the storage limit from #2713 (reverted in #2715) with an
exception for staff identities so our own account isn't blocked.

saas/lib/fizzy/saas/engine.rb

@@ -133,10 +133,14 @@ module Fizzy
       end
 
       config.to_prepare do
+        ::Account.include Account::StorageLimited
         ::Identity.include Authorization::Identity, Identity::Devices
         ::Session.include Session::Devices
         ::Signup.prepend Signup
         ApplicationController.include Authorization::Controller
+        CardsController.include(Card::StorageLimited::Creation)
+        Cards::CommentsController.include(Card::StorageLimited::Commenting)
+        Cards::PublishesController.include(Card::StorageLimited::Publishing)
 
         Notification.register_push_target(:native)