Improved reason reporting on SCSessionDidFail notification and added code

darcs-hash:20090217094709-58103-551e5b4193061be70336d6afb86bd195cfda29a1
On session failure print code (if present) in sip_audio_session.py

darcs-hash:20090217094801-58103-b9d738c22b437eb8de1cee7dedb186a74aed43f9