Added method `#eql?` to `ActiveSupport::Duration`, in addition to `#==`.

Currently, the following returns `false`, contrary to expectation:

    1.minute.eql?(1.minute)

Adding method `#eql?` will make this behave like expected. Method `#eql?` is
just a bit stricter than `#==`, as it checks whether the argument is also a
uration. Their parts may be different though.

    1.minute.eql?(60.seconds)  # => true
    1.minute.eql?(60)          # => false
Don't autosave unchanged has_one through records
Added Responders docs, made Web Console docs more consistent. [ci skip]
Backwards compat for activerecord-deprecated_finders

Maintain compatibility for:
* ActiveRecord::Base#find(:all)
* ActiveRecord::Base#find(:first)
* ActiveRecord::Base#find(:last)
OMG mysql!
Allow YAML serialization when using TZ aware attributes
Merge pull request #16929 from kongregate/fix-activerecord-deprecated_finders-find-symbol

ActiveRecord deprecated finders are broken in 4.2
Merge pull request #11794 from yoazt/duration-eql

Added method `#eql?` to `ActiveSupport::Duration`, in addition to `#==`.

Conflicts:
	activesupport/CHANGELOG.md
	activesupport/lib/active_support/duration.rb
	activesupport/test/core_ext/duration_test.rb
Merge pull request #16943 from sgrif/sg-fix-tz-converter-serialization

Allow YAML serialization when using TZ aware attributes
Merge pull request #16875 from alan/dont_autosave_has_one_through_record

Don't autosave unchanged has_one through records

Conflicts:
	activerecord/CHANGELOG.md
Use has_attribute?
[ci skip] AJ docs fixes
1. Indentation
2. Spaces issues
3. Spelling correction
4. Grammar correction
5. Add #:nodoc: to all internal classes
Merge pull request #16944 from akshay-vishnoi/docs-rails-4point2

[ci skip] AJ docs fixes
Merge pull request #16930 from todd/upgrade_guide

Added Responders docs, made Web Console docs more consistent. [ci skip]
[ci skip] ActiveSupport CHANGELOG fixes
1. spacing issues
2. spelling correction
3. grammar correction
4. Add missing docs
Merge pull request #16948 from akshay-vishnoi/docs-rails-4point2

[ci skip] ActiveSupport CHANGELOG fixes
Grammar correction in ActiveSupport CHANGELOG [ci skip]
Merge pull request #16950 from akshay-vishnoi/docs-rails-4point2

Grammar correction in ActiveSupport CHANGELOG [ci skip]
[ci skip] ActiveModel CHANGELOG docs fixes
Merge pull request #16952 from akshay-vishnoi/docs-rails-4point2

[ci skip] ActiveModel CHANGELOG docs fixes