Simplify the visited share rooms arrangement by making the share room
records a resource used only by the public share rooms objects (collection
and models).  This removes the need for the
ShareRoomRecordModel.getPublicShareRoom() method, and simplifies the view
activity.

It still leaves the issue of getting the fetched share room info into the
view, but at least addressing it will not be obscured by the incidental
ShareRoomRecordModel machinery.