Exercise 2i sort parameter

The order when sort is off is undefined, but this test at least tries
to verify that results are sorted when it's set or defaults to true.
Notice that sort order is not key, but rather <2i term that matched>, then key

This requires the following branches:

* https://github.com/basho/riak_pb/pull/66
* https://github.com/basho/riak-erlang-client/pull/130
* https://github.com/basho/riak-erlang-http-client/pull/27
* https://github.com/basho/riak_kv/pull/671