Add beep on event.
Hi,

Add possibility to make a beep on a event (getTopic and onValue or offValue)  : 

For example : 
{
      "name": "Porte 1",
      "setTopic": "dumy/garage/porte/status/set",
      "getTopic": "dumy/garage/porte/status",
      "onValue": "open",
      "offValue": "close
      "alarmValue": "open,5"
	},

In this example, it generate a beep during 5 seconds when getTopic take the value "open"
This alarm is ringing only with external event (ie i don't have push button on ESP to change the state)

Thanks. 