Basic pluto test of transport mode through NAT, using IKEv1

This time behind a NAT, (see transport-01)

A single transport mode SA is created between north and east, for port 7.

Note packets sent to port 2 and port 7 expect a connection refused. It is
enough to test packet flow (and on namespaces we dont have sshd running,
and we don't really need to start a daemon now)
