Two more modules updated

Two of the last three modules that were not ported to use the new sip router core are ready now: nat_traversal and siptrace.

Particularly, siptrace was refurbished a lot. Before release, there are couple of new features that should get in trunk since sip route core offers support for such extensions:

- ability to filter the ACK for negative replies issued by sl module in the script

- ability to store stateless forwarded messages (now only stateful ones being stored)

Testing is very much appreciated, see guidelines at Kamailio 3.0 Config wiki page.