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.
It should be noted that we don't currently support ring-resizing with strong consistency. However, if it's a new cluster,  the same recommendations probably apply as before for vnode/node counts.