cmd/loop: fix bug in optional swep addr parsing

In this commit we fix a recently introduce bug (when the addr kwarg was
added) that caused all commands to fail with an error. The issue was we
didn't advance the args linked list to the final element.

cmd/loop/loopout.go

@@ -50,6 +50,7 @@ func loopOut(ctx *cli.Context) error {
 	}
 
 	var destAddr string
+	args = args.Tail()
 	switch {
 	case ctx.IsSet("addr"):
 		destAddr = ctx.String("addr")