Add event for scheduler finish

Hi ajay_reddy,
This is an interesting idea, but I have several concerns and question:

1. Scheduler already provides an event for each time an entity is processed in a cron run. I am not sure of the benefit of having another event at the end
2. The individual events have the entity that has been processed, but your new event will not know anything about which entities have been processed, so I'm not sure how useful it is
3. The new event is being dispatched at the end of cron run, regardless of whether Scheduler actually processed any entity. That is a lot of overhead, and gives no real benefit
4. The event has a boolen parameter, defaulting to TRUE, but it is not explained what this means, or when it would be FALSE
5. All new features should have test coverage so that we can see that it is working and does what is intended

I'm not saying no, but I am also not yet convinced that we need this.
Jonathan