This tests the RFC3706 DPD implementation, with dpdaction=clear on east,
and dpdaction=restart on west. This is identical to dpd-01, but now we
are using Aggressive Mode.

This means east will clear the SA after the tunnel times out, while west
will put the route into %trap, awaiting a new packet to trigger reestablishment
of the tunnel.

Order of Operations:

1) East sets up for tunnel
2) West initiates tunnel to east
3) We idle for 20 seconds, to prove that DPD R_U_THERE/R_U_THERE_ACKs work.
4) West blocks traffic on eth0
5) Both sides trigger a DPD Timeout:
	East clears the eroute & SA
	West puts the eroute into %trap
6) West removes the traffic block
7) West sends icmp packets to east, triggering a renegotiation of the tunnel