Inline AttachmentVisibility method into Whitehall::Exporters::Mappings
Inline AttachmentVisibility method into Whitehall::Exporters::Mappings

I'm planning to get rid of the AttachmentVisibility class altogether.
This is a small step in that direction.

alphagov/whitehall,alphagov/whitehall,alphagov/whitehall,alphagov/whitehall