Update Riak CS test runner for Riak 2.0

Most of this file has already been copy-pasted from rtdev.erl. We'd like
to eventually fix that, but in the interest of getting the tests
running, this commit just brings it back up to date, using the same
technique.
Merge pull request #443 from basho/feature/update-cs-test-runner-for-riak-2.0

Update Riak CS test runner for Riak 2.0