Renamed use_audio and audio_proposed attributes to session.py to audio

darcs-hash:20090220115721-58103-63518a57cb23a983a7f859d40655e556c36f0bae
Changed pause_time between ringtone from 0.5 to 1 second

darcs-hash:20090220120924-58103-329ef0954ac3b5d8fed444b742abcf85e422056f