cleanup nintendo_nas_server and implement stub /pr handling

Just some cleanups.

nas.nintendowifi.net/pr is supposed to accept a string and return the number of "banned" words used in the string but for now we just return 0 ever time.

Also, technically parse_authtoken() could be removed since it's just a stub for the db function but I left it in in case the way getting the authtoken data changes in the future.