allocsim: Record and display the number of lease transfers per node
allocsim: Record and display the number of lease transfers per node

The display format is kind of awkward, so suggestions for cleaning it up
would be very welcome. I was trying to avoid making the output even
wider than it already is.

paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach