Add channels to handle closing and confirmations

[Gsantomaggio]

With this PR is possible to handle the consumer closing with dedicate channel:

channelClose := make(chan stream.Event, 1)
go func() {
    event := <-channelClose
    fmt.Printf("Consumer: %s closed on the stream: %s, reason: %s \n", event.Name, event.StreamName, event.Reason)
 }()

confirmation:

	chPublishConfirm := make(chan []int64, 1)
	go func(ch chan []int64) {
		messagesIds := <-ch
		fmt.Printf("Confirmed %d messages \n \n ", len(messagesIds))
	}(chPublishConfirm)