[enh] return exit values on daemon status

Created by: M5oul

#668 (closed):

• https://nodejs.org/api/process.html#process_exit_codes
• this will allow me to partially fix:
  • https://github.com/YunoHost-Apps/duniter_ynh/issues/21
  • stop daemon will only be done when daemon running.

duniter stop
echo $?
2
duniter start
echo $?
0

bin/daemon

@@ -20,10 +20,11 @@ switch (process.argv[2]) {
   case "status":
     if (daemon.status()) {
       console.log('Duniter daemon status: running');
+      process.exit(0)
     } else {
       console.log('Duniter daemon status: stopped');
+      process.exit(2)
     }
-    break;
 
   case "sync":
   case "reset":