lnd+macaroons: specify location when creating macaroon service

To allow the macaroon service to be used in other projects, we want the
location to be passed in as a parameter instead of being hard coded.

lnd.go

@@ -393,7 +393,7 @@ func Main(cfg *Config, lisCfg ListenerCfg, shutdownChan <-chan struct{}) error {
 	if !cfg.NoMacaroons {
 		// Create the macaroon authentication/authorization service.
 		macaroonService, err = macaroons.NewService(
-			cfg.networkDir, macaroons.IPLockChecker,
+			cfg.networkDir, "lnd", macaroons.IPLockChecker,
 		)
 		if err != nil {
 			err := fmt.Errorf("unable to set up macaroon "+