Re-target Yokozuna to Riak 1.4.0

*This PR isn't ready to be merged*

Update yokozuna to work against the 1.4 master changes. This branch relies on:

* <del>[KV yz-merge-1.4.0 branch](https://github.com/basho/riak_kv/compare/yz-merge-1.4.0)</del>
* <del>[Riak yz-merge-1.4.0 branch](https://github.com/basho/riak/compare/yz-merge-1.4.0)</del>

NOTE: These test still fail for me

* yz_pb-bitcask
* yz_mapreduce-bitcask
* yz_flag_transitions-bitcask