rgy.py: make log_(data|metadata) configurable
rgy.py: make log_(data|metadata) configurable

The log_data and log_metadata are made configurable
via the YAML file and default to false
(meaning neither data nor metadata operations are
logged).

Signed-off-by: Joe Buck <a95e51950b61b017a762bcc8a962bac0b1a073a0@gmail.com>
Reviewed-by: Josh Durgin <51652c783f70f5b272ebd02f1fd20d3af7a2449f@inktank.com>

michaelsevilla/teuthology,ceph/teuthology,ivotron/teuthology,robbat2/teuthology,dmick/teuthology,michaelsevilla/teuthology,dreamhost/teuthology,SUSE/teuthology,SUSE/teuthology,t-miyamae/teuthology,ceph/teuthology,caibo2014/teuthology,ktdreyer/teuthology,caibo2014/teuthology,dmick/teuthology,robbat2/teuthology,zhouyuan/teuthology,dmick/teuthology,dreamhost/teuthology,tchaikov/teuthology,yghannam/teuthology,zhouyuan/teuthology,yghannam/teuthology,t-miyamae/teuthology,SUSE/teuthology,ktdreyer/teuthology,tchaikov/teuthology,ivotron/teuthology