Added support for RFC5768 (ICE option tag)

Ignore-this: 53a2364d4a3013ccce20a391bd1b0a2c

darcs-hash:20130613140516-56b4d-330e95d29f744ff2e6bd19864d31f49a719bf736
Removed NAT detector from SIPApplication

Ignore-this: 5afbddc592e05ad4fe5fc748c476df3

darcs-hash:20130613150935-56b4d-11a52fa1c30c15bea6d7fc7e63ee5a172688b96f