added party full notification sound
changed notification sound to "turn bell" which is better
added game_config::sounds::party_full_sound, defaults to turn bell
and switched multiplayer_connect.cpp to use this sound
changed debugging output message
changed the logic for the bell:
connect engine must report no sides are available and game can start.
add self to about.cfg
Merge pull request #85 from cbeck88/party-full-bell

Party full bell