rgw: init_rest: small refactoring
rgw: init_rest: small refactoring

The validation function has been updated to handle empty bucket names.
Empty key names also pass validation.

Signed-off-by: Colin McCabe <7b35906f1d014e74a9dc8c913eb229119df647aa@dreamhost.com>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph