Disconnect after a timeout (#842)

So as to save the devices battery

main/ZgatewayBT.ino

@@ -569,6 +569,8 @@ void BLEconnect() {
               if (pRemoteCharacteristic->canNotify()) {
                 Log.trace(F("Registering notification" CR));
                 pRemoteCharacteristic->subscribe(true, notifyCB);
+                delay(BLE_CNCT_TIMEOUT);
+                pClient->disconnect();
               } else {
                 Log.notice(F("Failed registering notification" CR));
                 pClient->disconnect();

main/config_BT.h

@@ -56,6 +56,7 @@ extern void MQTTtoBT(char* topicOri, JsonObject& RFdata);
 #define BLEdelimiterLength 16
 #define CRLR               "0d0a"
 #define CRLR_Length        4
+#define BLE_CNCT_TIMEOUT   3000
 
 #define ServicedataMinLength 29