[Serusers] nathelper support for Ottendorf

[Ladislav Andel]

Hi all,
I have added nathelper support to basic ser.cfg file of Ottendorf release.
It is a simple setup without any complexity of using other features such 
as connectivity_realm etc.
You can download it at 
http://www.iptel.org/ser/howtos/optimizing_the_use_of_rtp_proxy
File is called ser_config_2_0.txt

The more complex one will come with updated document soon.

Lada