Added a modify endpoint to change name and port

main.go

@@ -129,6 +129,15 @@ func main() {
 
 		sendIPCRequest(cfg, "POST", fmt.Sprintf("/instances/delete?name=%s&purge=%s", url.QueryEscape(name), url.QueryEscape(strconv.FormatBool(*purge))), nil)
 
+	case "modify":
+		if len(args) < 4 {
+			log.Fatalf("Usage: vssm modify <instance_name> <new_name> <new_port>")
+		}
+		name := args[1]
+		newName := args[2]
+		newPort := args[3]
+		sendIPCRequest(cfg, "POST", fmt.Sprintf("/instances/modify?name=%s&newName=%s&newPort=%s", url.QueryEscape(name), url.QueryEscape(newName), url.QueryEscape(newPort)), nil)
+
 	default:
 		printUsage()
 	}