rgw: fix error code of inexistence of versions location in swift api

rgw: fix error code of inexistence of versions location in swift api

when the versions location of container does not exist and uploading the same
object two more times to the container, it will return 412 rather than 404
in openstack swift. Meanwhile, if the dest bucket owner is not consistent with
src bucket owner, it will return 412.

http://tracker.ceph.com/issues/18880
Signed-off-by: Jing Wenjun <jingwenjun@cmss.chinamobile.com>