rgw-admin: Adds --metadata-key option to help
Signed-off-by: Christophe Courtaut <christophe.courtaut@gmail.com>
Merge pull request #587 from kri5/master

rgw-admin: Adds --metadata-key option to help

Reviwed-by: Yehuda Sadeh <yehuda@inktank.com>
Merge git://github.com/ceph/ceph