Check group grants even if user has other grants specified in the ACL.
Check group grants even if user has other grants specified in the ACL.

Fixes #177

Group grants were ignored if the user issuing the request had other
permissions in the ACL. This change makes sure group grants are also
check in that case.

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