This is a tool to help developers quantify changes to the ring
builder. It takes a scenario (JSON file) describing the builder's
basic parameters (part_power, replicas, etc.) and a number of
"rounds", where each round is a set of operations to perform on the
builder. For each round, the operations are applied, and then the
builder is rebalanced until it reaches a steady state.
The idea is that a developer observes the ring builder behaving
suboptimally, writes a scenario to reproduce the behavior, modifies
the ring builder to fix it, and references the scenario with the
commit so that others can see that things have improved.
I decided to write this after writing my fourth or fifth hacky one-off
script to reproduce some bad behavior in the ring builder.
Change-Id: I114242748368f142304aab90a6d99c1337bced4c
ccf0758ef1