Added properties with RTP endpoint information to AudioStream

Ignore-this: 391d454da66bdec151fd7023d5d358f4

darcs-hash:20090716145017-1e3d8-c9397624cd447412caf6796840cfa782d14bbe41
Added srtp_active property to AudioStream

Ignore-this: 1e810d2253179afa69a3171cbaf26e82

darcs-hash:20090716145233-1e3d8-cf6b92830ecef9138ad106d7d33d6312d2c2f607