Add two configuration options for no_ack and no_rtp

darcs-hash:20090509191752-58252-6eb518a639c11795c490b281447887f05e058059
Ignore SIPCoreError when unregistering during Account deactivation

darcs-hash:20090511112513-58103-3151fd41da1d0998a98f7262bcf603d304f53837