cardiff: Adding sample output file for network test

Useful to test cardiff.
health: Saving original yaml file

When running a benchmark, let's save the original yaml file that could
be reused to replay this bench.
health: Dumping host affinity everytime we discover new VMs

This is very useful when some VMs are not able to connect.
That could help levering that a particular HV is not working as
expected.