Allow timers for checking incoming RTP of AudioTransport to be 0

darcs-hash:20090511130708-58103-81062c6985e9ad29b9e31bb0a58e1fd2e0a393df
Added Account.audio.media_timeout setting

darcs-hash:20090511132253-58103-1bd239eb143ea96625f028eac67ecdc9f2c6f2d5