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 change `N of 3` to `n_val of 3` or `N=3`. 
`N of 3` sounds weird to me.