cmd/loop: add initiator to swap requests

cmd/loop/loopin.go

@@ -150,6 +150,7 @@ func loopIn(ctx *cli.Context) error {
 		ExternalHtlc:   external,
 		HtlcConfTarget: htlcConfTarget,
 		Label:          label,
+		Initiator:      defaultInitiator,
 	}
 
 	if ctx.IsSet(lastHopFlag.Name) {

cmd/loop/loopout.go

@@ -195,6 +195,7 @@ func loopOut(ctx *cli.Context) error {
 		HtlcConfirmations:       htlcConfs,
 		SwapPublicationDeadline: uint64(swapDeadline.Unix()),
 		Label:                   label,
+		Initiator:               defaultInitiator,
 	})
 	if err != nil {
 		return err

cmd/loop/main.go

@@ -48,6 +48,10 @@ var (
 	// that we set when sending it over the line.
 	defaultMacaroonTimeout int64 = 60
 
+	// defaultInitiator is the default value for the "initiator" part of the
+	// user agent string we send when using the command line utility.
+	defaultInitiator = "loop-cli"
+
 	loopDirFlag = cli.StringFlag{
 		Name:  "loopdir",
 		Value: loopd.LoopDirBase,