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.
There are 2 reasons you would need to set trust_lease to false. 1) If your clocks didn't tick at the same rate due to not having proper posix monotonic clocks or buggy erlang clock being interfered with by ntp. 2) If your tick timeouts were incorrectly configured. I believe there is an outstanding issue to not allow tick timeouts that compromise leases.  There is a specific hierarchy for these ticks described in Joe's docs here: https://github.com/basho/riak_ensemble/blob/wip/riak-2.0-user-docs/riak_consistent_user_docs.md#leader-leases and configured by default.