🎯 Create @EventCancelationHandler annotation

[nuriofernandez]

Create something to control event cancelations. From exceptions to manual cancelations.

For example:

@EventCancelationHandler
public void onCancelMessage(MessageSendEvent event) {
    System.out.println("Message from " + event.getUser().getName() + " has been cancel");
}

[nuriofernandez]

With the completion of the issue #25 now we can complete this one by embedding a new event manager inside the main one. Handling only the @EventCancelationHandler annotation. 🧩