Don't expose tracebacks to users on 500 error
Don't expose tracebacks to users on 500 error

The error is still logged to error.log, so it is not hidden.

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