rkt: Fix /etc/hosts /etc/resolv.conf permissions

This enables any users on the container to resolve DNS, instead of only root.

pkg/kubelet/rkt/rkt.go

@@ -659,7 +659,7 @@ func copyfile(src, dst string) error {
 	if err != nil {
 		return err
 	}
-	return ioutil.WriteFile(dst, data, 0640)
+	return ioutil.WriteFile(dst, data, 0644)
 }
 
 // TODO(yifan): Can make rkt handle this when '--net=host'. See https://github.com/coreos/rkt/issues/2430.