Always relying on the responses when crossing NAT's are not a good

solution, it breaks communication.
Rizzo - you need to implement a configuration option for this 
code. It's good, but maybe should be off by default.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@89285 65c4cc65-6c06-0410-ace0-fbb531ad65f3