Refactored sipsimple.account using a green model

Ignore-this: 5d416505bcb11d842c888dbf8759a84d

darcs-hash:20100105094323-1e3d8-9f6fe98ede89a4da5abe8287d2dc6a3cbed051d8
Restrucutred SIPApplication to simplify the code

Ignore-this: afde7e75b3f9ce9d49f46e0fce911283

darcs-hash:20100105094356-1e3d8-54c7340ae7cfb1286856b440134b4f723e458c30