We shouldn't be overriding this. soft-deleted objects are still
persisted.

The default implementation is already destroy || raise

Thanks @kidlab

There was a change in ActiveRecord#update_columns on latest rails
so now it checks for `destroyed?` instead of `persisted?`. Paranoia
can't override `destoyed?` like this anymore otherwise
`update_columns` will always raise:

        ActiveRecord::ActiveRecordError: cannot update a destroyed record

see https://github.com/rails/rails/commit/0f99aa615e11c50cc64b567f54cf64f59108c5e5

If the association object is a has_one relationship with an :as option,
it will have a type attribute (see
https://github.com/rails/docrails/blob/master/activerecord/lib/active_record/reflection.rb#L280).

If this type attributes is present, that will be the type column on the
polymorphic model. The foreign key can be found as an attribute on
the association object.

The changes in 40b7af58 were insufficient, this should do the trick.

FIX: where("association_id", id) leads to invalid statement in postgres. where should just be given a hash.

This reverts commit 4004bd5e.

This reverts commit 6881e750.

see https://github.com/radar/paranoia/issues/169

refs https://github.com/radar/paranoia/issues/102

This appears to be a Rails ~> 4.0.8 bug, which is seemingly fixed in Rails 4.1.

Use fetch for sentinel_value

Use DateTime for sentinel_value example

Use an epoch. rails convers '0' or 0 to nil for datetime fields

Add test for restore

Update readme

Move MYSQL note to bottom of readme

update destroyed? for sentinel value

This reverts commit 566b1cbd.

Conflicts:
	README.md
	test/paranoia_test.rb

Fixes #149

Fixes #148