Added support for MSRPDesktop in Session

Ignore-this: fff28a097824c08ade94fd5c90a69046

darcs-hash:20090821112414-1e3d8-758f87a4de3e1c0e121022a947cc715a57f1a816
Adapted sip_message script to using the SIPApplication class

Ignore-this: 260e5be6e71e41f9f9cbb46ff397edbd

darcs-hash:20090821123348-1e3d8-90454c13209e5bbd2b7a82b6f5fa74103fbc722a