move/converge yz_rt (helper mod) in yz repo to yokozuna_rt in r_t repo [JIRA: RIAK-2576]

[zeeshanlakhani]

• eventually code will live w/ tests
• but all helper funs can go together
• files referenced -> https://github.com/basho/yokozuna/blob/2.0/riak_test/yz_rt.erl (2.0 version, but same goes for others) & https://github.com/basho/riak_test/blob/master/src/yokozuna_rt.erl