Fix regression in 2i reformat status flag & add extra status function

This PR fixes a regression introduced by [1] (see commit/patch for more details) and adds `riak_kv_status:fixed_index_status` which is meant to be used by riaknostic


[1] https://github.com/basho/riak_kv/commit/b50d1df73aee20c4260e72d73fdfcf6493603636