delete_all will call callbacks if depdent option is specified as
:destroy. This behavior is not very clear from the documetation and
hence issue #7832 was raised.

closes #7832

This reverts commit 637a7d9d, reversing
changes made to 5937bd02.

* dependencies/autoload
* concern
* deprecation

particularly, `all(options)` would warn

To perform a sum calculation over the array of elements, use to_a.sum(&block).

Please check the discussion in f9cb645d
for more context.

Callbacks may interfere with each other.

Fixes #3458.

Exception message was misleading, as it is possible to have a
polymorphic 'has_many :through' join model.

I've noticed a caveat with the :autosave option biting people before.
Questions arise about why they must explicitly save an associated object
in their own before_save callbacks. I've updated the documentation as
such to note to users that the :autosave callback occurs before any
user defined callbacks. They must save the associated record themselves
if altering it in their own callbacks.
Signed-off-by: NDavid Celis <david@davidcelis.com>

It's not really a good idea to have this as a global config option. We
should allow people to specify the behaviour per association.

There will now be two new values:

* :dependent => :restrict_with_exception implements the current
  behaviour of :restrict. :restrict itself is deprecated in favour of
  :restrict_with_exception.
* :dependent => :restrict_with_error implements the new behaviour - it
  adds an error to the owner if there are dependent records present

See #4727 for the original discussion of this.

This reverts commit 3fb0100e.

This reverts commit 3803fcce.

Conflicts:
	activerecord/CHANGELOG.md

It will be deprecated only in 4.0, and removed properly in 4.1.

This fixes active_record_deprecated_finders.