Added enable_extension! to helper
Do not mark object as persisted after an association is saved

Callback order in Active Record objects are important. Users should not
define callbacks before the association definition or surprising
behaviours like the described at #3798 will happen. This callback order
dependency is documented at https://github.com/rails/rails/blob/31bfcdc77ca0d8cec9b5fe513bdc6f05814dd4f1/activerecord/lib/active_record/associations.rb#L1222-1227.

This reverts #15728.

Fixes #16620.
Remove CHANGELOG entry [ci skip]
Merge pull request #16114 from seuros/test_clean

[Postgresql tests] Added enable_extension! to helper
Add TODO to release the gems before the next Rails release
Use the released jquery-rails gem
Dependencies: bump to jquery-rails 4.0.0.beta2
Fix query with nested array in Active Record

`User.where(id: [[1,2],3])` was equal to `User.where(id:[1, 2, 3])`
in Rails 4.1.x but because of some refactoring in Arel this stopped
working in 4.2.0. This fixes it in Rails.

[Dan Olson & Cristian Bica]