Remove entity events from delegateEvents/undelegateEvents

This may be very minor or even a non-issue... certainly less of an issue until the next backbone release.

Backbone.View.delegateEvents is for explicitly setting up events on the.$el and this is even more evident with this PR for an upcoming release:  https://github.com/jashkenas/backbone/pull/3060

Marionette Entity events don't need to be re-setup if the $el changes.

Really it seems they may need only be bound in the constructor and cleaned up, as they will be anyways, on destroy.  Then if you needed to dynamically change collectionEvents or modelEvents for some reason, you'd use Marionette.View.bindEntityEvents

However a change like this would be breaking for anyone currently using delegateEvents as a reset for if changes are made to modelEvents or collectionEvents.
We should probably have a method for delegating and undelegating these events with before and after trigger methods. 

```js
delegateViewEvents: function() {
   this.triggerMethod('before:delegateview:events');
   this.bindEntityEvents(this.model, this.getOption('modelEvents'));
   this.bindEntityEvents(this.collection, this.getOption('collectionEvents'));
   this.triggerMethod('before:delegate:view:events');
}
```

thoughts?