added String#to_date documentation to Rails 4 upgrade guide

[ci skip]
Make 'enable_extension' revertible

If 'enable_extension' is used in a migration's 'change' method, use
'disable_extension' on down migration (and vice-versa).
Execute conditional procs on controller filters only for current action.

:only and :except options for controller filters are now added before
:if and :unless. This prevents running :if and :unless procs when not
on the specified. Closes #11786.
Merge pull request #11799 from njakobsen/fix-controller-filter-callbacks

Execute conditional procs on controller filters only for current action
Merge pull request #11826 from etipton/enable_extensions_revertible

Make 'enable_extension' revertible
only reconnect if there was already an active connection

If you're using an in-memory database for the test database,
reconnecting will lose all information that schema:load did for us.
chmod -x
Upgrade ActiveRecord-JDBC-Adapter to master branch

Switch to master branch which provides Version 1.3.x of AR-JDBC adapter.
It strives to provide ActiveRecord 4.x compatibility (as well as still supporting 2.3 and 3.x) from a single code base. It's a recommended update for all AR-JDBC 1.2.x users.
drop extra variable
Merge pull request #11846 from gaurish/jdbc-upgrade

Upgrade ActiveRecord-JDBC-Adapter to v1.3 for better compatibility with ActiveRecord 4
Fix interactions between :before_add callbacks and nested attributes assignment

Issue #1: :before_add callback is called when nested attributes assignment assigns to existing record if the association is not yet loaded
Issue #2: Nested Attributes assignment does not affect the record in the association target when callback triggers loading of the association
Restore the use of `#add_to_target` for nested attribute updates on existing records, and don't bother updating the association if the update is going to be rejected anyway.

This requires adding a `skip_callbacks` argument to `#add_to_target`
so that we don't call the callbacks multiple times in this case,
which is functionally an application of existing association data,
rather than an addition of a new record to the association.
Refactor NestedAttributesWithCallbacksTest for clarity

1) Use `assert` and `refute` where possible.
2) Separately include the setup, subject, and assertions in each test - don't hide the tested call in an assertion method.
3) Name things based on their role rather than incidental facts about them - e.g. `@bird[1]` -> `bird_to_destroy`. `bird2_deletion_attributes` -> `destroy_bird_attributes`.
4) Use more succinct naming where possible - e.g. `birds_with_callback` -> `birds_with_add`, `@pirate_with_two_birds` -> `@pirate`
Merge pull request #11525 from Empact/nested_attributes_with_callbacks_bug

Improve #5476 - "Nested attributes with callbacks bugfix" to use add_to_target and clearer tests
Use assert_not rather than refute
Merge pull request #11838 from vipulnsward/drop_extra_var

drop extra variable
Added comment to a guide about necessity of `:dependent` option for associations with NOT NULL constraint
Merge pull request #11852 from prijutme4ty/guide_addition

Added comment to a guide about necessity of `:dependent` option for asso... [ci skip]
Add events reference link to the text about jquery-ujs [ci skip]
Merge pull request #11823 from fomede/add-jquery-ujs-reference-link

Add events reference link to the text about jquery-ujs [ci skip]