Send Via based on SIPFILE instead of autogeneated

-i option prevents Via from being generated.
Now we generate it in SIPFILE. This prevents
hostname looking for the Via header and we can
use [% sip_int_ips.0 %] for it

BRANCH for the Via header is autogenerated by UUIDGEN command

-l 5081 forces the source port for sending requests to be that one

-S forces symetric mode and makes Sipsak listen in the same 5081 port