thermostat: switch payload to 1/0, it will be easier for external mqtt parsing

soft/thermostat/src/mainwindow.cpp

@@ -213,7 +213,7 @@ void MainWindow::apply_automatic_state(void)
 		qDebug() << "heater " << h->ctrl_topic;
 			/* TODO: check if connected */
 			m_mqtt->publish_msg(h->ctrl_topic,
-					    m_zones.at(i)->m_heating_on ? "on" : "off");
+					    m_zones.at(i)->m_heating_on ? "1" : "0");
 		}
 	}
 }

soft/thermostat/src/mqttclient.cpp

@@ -121,7 +121,7 @@ void MQTTClient::publish_msg(const QString& topic, const QString& payload)
 void MQTTClient::allHeatersOn(bool on) {
 	Settings *s = Settings::getInstance();
 
-	QString payload = on ? QString("on") : QString("off");
+	QString payload = on ? QString("1") : QString("0");
 
 	for (int i = 0; i < s->nbZones(); i++) {
 		const struct Room *r = &(s->m_rooms.at(i));