Refactor LED management (#745)

-replace low power led by led info
-enable to change the led ON value
-go upper case for the led macros

Also transform BLE connect warning to notice in log
Add Sonoff RF Bridge LED

docs/use/gateway.md

@@ -7,3 +7,18 @@
 ## Erase the ESP settings
 
 `mosquitto_pub -t "home/OpenMQTTGateway/commands/MQTTtoSYS/config" -m '{"cmd":"erase"}'`
+
+# State LED usage
+
+The gateway can support up to 3 LED to display its operating state:
+* LED_INFO 
+switched ON when network and MQTT connection are OK
+5s ON, 5s OFF when WIFI is disconnected
+1s ON, 4s OFF when MQTT is disconnected
+
+* LED_RECEIVE
+Blink for `TimeLedON` 0.5s when the gateway receive a signal from one of its module so as to send to MQTT
+
+* LED_SEND
+Blink for `TimeLedON` 0.5s when the gateway send a signal with one of its module from an MQTT command
+