fix 500 at GETting /riak-cs/ping - due to lack of argument
fix 500 at GETting /riak-cs/ping - due to lack of argument

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