Handle #delete_all

[mohammednasser-32]

Goal

Add support for delete_all method, taking into account that delete_all can be called on both Class and ActiveRecord::Relation, example:

User.delete_all
User.where(id: [1,2,3]).delete_all

The feature is wrapped by a setting that can be enabled globally using

Paranoia.delete_all_enabled = true

Or for specific models

acts_as_paranoid(delete_all_enabled: true)

Fixes Issue#565
Fixes Issue#538