plugin/forward: add REFUSED test (#1878)

add a test to see if we copy the rcode correctly. Some minor cleanup in
import ordering and renaming NewUpstream to New as we already are in the
upstream package.

plugin/kubernetes/setup.go

@@ -218,7 +218,7 @@ func ParseStanza(c *caddy.Controller) (*Kubernetes, error) {
 			k8s.Fall.SetZonesFromArgs(c.RemainingArgs())
 		case "upstream":
 			args := c.RemainingArgs()
-			u, err := upstream.NewUpstream(args)
+			u, err := upstream.New(args)
 			if err != nil {
 				return nil, err
 			}