added delete_quietly method on Model

[JarriqTheTechie]

This method calls the delete method on a model without firing the delete & deleting observer events. Instead of calling:

User().delete(...)

you can use this:

User.delete_quietly(...)

[JarriqTheTechie]

@girardinsamuel / @josephmancuso please review.

[Marlysson]

Shouldn't activate again the events after this operation as save and updte quietly does with .with_events() method?

[JarriqTheTechie]

Thanks @Marlysson @josephmancuso