Adding support to cancel "restore" and "real_destroy" actions

[arieliten]

Currently the callbacks for before_restore and before_real_destroy can't be canceled (via returning false) like any other normal ActiveModel::Callback. So here I'm adding the support to cancel any of those actions (restore or real_destroy) by returning false in their callbacks.

[rbr]

Canceling callbacks with falseseems to be deprecated in Rails 5: rails/rails#17227, throw(:abort) is the new way.

[valentindruon]

What if we are not using Rails 5.0?

[therrick]

I'd love to see this get merged. We've been using a custom fork with this change for several months now and would much rather have it in the main repo. Any outlook for accepting it?

[BenMorganIO]

Good job @arieliten. Can you provide a test for this change?

[kasparsj]

+1