[ONOS-YANG-DEMO1]Configurations are getting configured on only one device for multiinstance case.

I have analysed the multi instance problem and found that it's not related to Mastership Role change issue, rather it was a BUG in NetconfActiveComponent:-

Earlier behaviour :-
When composite request for DELETE/POST was sent and below behaviour observed :
1. Some both the devices were getting configured
2. Some time only one of the device only getting configured.
3. Some none of the devices were getting configured

Root Cause :-
In active component when we collect all the events from store in InternalEventAccummulator, There we are getting the device id form the event-subject and checking for its master.

If ONOS instance is not master for the requested device , then it was returning from there and not even processing the other collected event in accumulator.

Code:-
checkNotNull(event, "process:Event cannot be null");
DeviceId deviceId = getDeviceId(event.subject());
if (!isMaster(deviceId)) {
log.info("NetConfListener: not master, ignoring config for {}", event.type());
return; <---- This was the problem
}

Behaviour Randomness :-
If first event received by any of the instance and same instance is master for that device, Then it was processing it and configuring it on device too.

Solution :-
In Active component if received event instance is not master of the requested device , then it suppose to drop that event and continue processing the other present event in accumulator.

I have incorporated the change in my branch also.