Fixed parsing of Warning header in _pjsip_msg_to_dict

Ignore-this: 5ad4ac27bbc51ee0c716143429bf39fe

darcs-hash:20090907125454-1e3d8-4b7c764033dcaf7af0e34b32a779fd3f750b0632
Changed RuntimeError in Session with IllegalStateError

Ignore-this: 1ff57b2f958b2746cd55ec34d5e62d0b

darcs-hash:20090907125553-1e3d8-600e926580860280256ba953d65e031837ecfcb9