Test the operation of list keys and buckets for undefined bucket types

Per defect [riak kv defect 875](https://github.com/basho/riak_kv/issues/875), the client hangs when a list keys operation is issued for a undefined bucket type.  Additionally, list buckets returns an ok rather than error.  This PR adds tests to verify that the client does not hang and returns the appropriate error when this condition occurs.  It verifies the changes introduced by [riak_kv PR 966](https://github.com/basho/riak_kv/pull/966).

This PR supersedes [616](https://github.com/basho/riak_test/pull/616) which has been closed due to the changes in the message, as well as, the need to properly squash all commits.

/cc @seancribbs @reiddraper @seancribbs