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.
I'd replace `to assist in servicing some requests` with:
`to perform long running k/v operations, thus allowing the peers to remain responsive to protocol requests.