rgw: follow olh if needed

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
rgw: update json encoding for rgw_obj

Signed-off-by: Yehuda Sadeh <yehuda@redhat.com>
rgw: object manifest should reflect instance

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