Simple Dealer-Router example with CurveZMQ authentication

Example based on
https://github.com/zeromq/pyzmq/blob/master/examples/security/ironhouse.py

Signed-off-by: Rodrigo Oliveira <rodrigo@simb.com.br>
Adding 'tcpdump.sh' script to analyze what's going on

Based on
http://lists.zeromq.org/pipermail/zeromq-dev/2013-March/020824.html

Signed-off-by: Rodrigo Oliveira <rodrigo@simb.com.br>