Active Support housekeeping and polish

https://github.com/rails/rails/commit/e7d55f734aae204115d0a04a2db774ac364c1312

This may break existing tests that are asserting the whole session contents
but should not break existing tests that are asserting individual keys - e.g:

class SomeControllerTest < ActionController::TestCase
  setup do
    session['user_id'] = 1
  end

  test "some test" do
    get :some_action, nil, { 'another_var' => 2 }

    # This assertion will now fail
    assert_equal({ 'another_var' => 2 }, session)

    # This assertion will still pass
    assert_equal 2, session['another_var]
  end
end

Fixes #1529.

Create plpgsql language if not available

Refactor AMo::Translation, avoid changing options in human attr name

Use Rails::Queueing::Queue instead of Queue so people can build their own consumers around stdlib's Queue

Refactor AMo::Errors

Improve AMo::Dirty *_will_change! method

removed deprecation warnings

This should fix the problem in Travis CI server.
(http://travis-ci.org/#!/rails/rails/jobs/1194988)

Add parentheses to hide Ruby warning

* Use merge!, remove reverse_merge
* Use case statement instead of is_a? checks

Avoid obtaining the value and duplicating it when possible.

Fix failing test related to TestQueue

Log the exception from the ThreadConsumer

This will make sure you know when there's an exception occur.

jobs.

Rails::Queueing::TestQueue run order

update docs - disabling prepared statements is not connected to managing connections externally [ci skip]