2712 dev scripts

[iamleeg]

Allow make_superuser.sh to make superusers on other instances (this is typically OK security-wise as the person needs to have write access to that DB so could already do it).

Allow setup_db.sh to import data to arbitrary local databases (this is not permitted on other databases as it someone could accidentally drop production data if they have the connection string set in their environment: I have nearly done this before!)

Update the documentation for the scripts.