Clean JSON output

rest.cpp

@@ -72,7 +72,6 @@ void identify() {
     unsigned long elapsed_seconds = (millis() - PINS.last_triggered) / 1000;
     message += "\"sec_since_interrupt\":";
     message += elapsed_seconds;
-    message += ",\n";
     message += "\n}";
 
     // TODO: Add here power sequence status