Ready: Strong consistency update

- [x] Configs in `advanced.config`
- [x] `riak-admin` interface for ensemble
- [x] Implementation details

Heads up to @andrewjstone, @engelsanchez, and @jtuple when he's back.
Note however, that you still want to limit the maximum number of vnodes per node to avoid unnecessary resource contention and the possibility of high latencies resulting from it. In general, the more nodes you have, or expect to have, the larger the ring. Probably best to put a link to http://docs.basho.com/riak/2.0.0/ops/building/planning/cluster/#Ring-Size-Number-of-Partitions in here as well. That section could probably also use some expanding.