While testing TCP & UDP tests (coming soon), I tracked down a bug in the IP addressing scheme used by xm-test: each machine running network tests is using the same IP addresses, so two machines in the same network can cross-pollinate/interfere with each other's tests.

This patch changes the IP addressing scheme to add some randomness. It's gone through a couple of dozen passes of xm-test, some on -bridge and some on -route, while xm-test was running on another box on the same network.

Signed-off-by: Jim Dykman <dyk...@us.ibm.com>