Feature/ensembles wait for riak kv

Test that ensemble peers will not start until the riak_kv service is up. This verifies https://github.com/basho/riak_kv/pull/989 and basho/riak_ensemble#32

Functionality was added to the intercepts so that they can save the generated modules in the basho-patches directory of a node, so that they can be loaded on startup. This should be useful to other tests that require modifying the behavior of Riak while it's starting up.  /cc @jburwell since you needed something like this recently.
Might be a good idea to make the sleep duration configurable.