trafgen: TCP SYN flood attack example for trafgen

Used when developing the iptables solution for SYNPROXY.
Making this public as the SYNPROXY solution is now public and
available in released kernels.

Blog:
 http://rhelblog.redhat.com/2014/04/11/mitigate-tcp-syn-flood-attacks-with-red-hat-enterprise-linux-7-beta/
 http://netoptimizer.blogspot.dk/2014/04/mitigating-ddos-syn-flood-attacks-with.html

Slides:
 http://people.netfilter.org/hawk/presentations/klid_2014/iptables-ddos-mitigation_JesperBrouer.pdf
 http://people.netfilter.org/hawk/presentations/devconf2014/iptables-ddos-mitigation_JesperBrouer.pdf

YouTube video:
 https://www.youtube.com/watch?v=BklSqr9t4uA

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Merge branch 'master' of github.com:netoptimizer/network-testing
 Forgot to pull before pushing change from my laptop