As an admin I want to be able to mark a place private

[longhotsummer]

A country or a locality. Only users with that badge should be able to see it.

• [ ] update PlaceSettings model to add a private field, which defaults to False and can be edited in the place settings page
• [ ] update PlaceViewBase (and possibly others) to check if user has appropriate country permissions
• [ ] update place listing page to exclude places for which the user doesn't have permission