Remove unused func and type
Remove unused func and type

AZ845

* Remove unused moss_client fun
* Remove unused `user` type

laurenrother/riak_cs,dragonfax/riak_cs,basho/riak_cs,laurenrother/riak_cs,laurenrother/riak_cs,basho/riak_cs_lfs,GabrielNicolasAvellaneda/riak_cs,GabrielNicolasAvellaneda/riak_cs,basho/riak_cs,basho/riak_cs_report,yangchengjian/riak_cs,basho/riak_cs,yangchengjian/riak_cs,GabrielNicolasAvellaneda/riak_cs,yangchengjian/riak_cs,sdebnath/riak_cs,sdebnath/riak_cs,basho/riak_cs,sdebnath/riak_cs,GabrielNicolasAvellaneda/riak_cs,laurenrother/riak_cs,yangchengjian/riak_cs,dragonfax/riak_cs,dragonfax/riak_cs,sdebnath/riak_cs,dragonfax/riak_cs