Merge pull request #8264 from cbodley/wip-rgw-admin-errors

radosgw-admin: 'period commit' supplies user-readable error messages

Reviewed-by: Yehuda Sadeh <yehuda@redhat.com>

diff --cc src/rgw/rgw_admin.cc
Simple merge

diff --cc src/rgw/rgw_rados.cc
Simple merge

diff --cc src/rgw/rgw_rados.h
Simple merge