backport runner fixes to 3-2-stable

Add a runner hook to Rails::Application and Rails::Engine that requires
ActiveRecord::Base to avoid circular constant loading when using observers.

This commit backports cc7dd66, c0ba0f0 and 8d01c61.
Add release date of Rails 3.2.9 to documentation

Conflicts:
	actionpack/CHANGELOG.md
	activerecord/CHANGELOG.md
	activesupport/CHANGELOG.md
updating the changelog for the CVE
updating the changelogs
updating changelog
CVE-2012-5664 options hashes should only be extracted if there are extra parameters
Merge branch '3-2-sec' into 3-2-secmerge

* 3-2-sec:
  CVE-2012-5664 options hashes should only be extracted if there are extra parameters
  updating changelog
  updating the changelogs
  updating the changelog for the CVE
  Add release date of Rails 3.2.9 to documentation

Conflicts:
	actionmailer/CHANGELOG.md
	actionpack/CHANGELOG.md
	activemodel/CHANGELOG.md
	activerecord/CHANGELOG.md
	activeresource/CHANGELOG.md
	activesupport/CHANGELOG.md
	railties/CHANGELOG.md
bumping version to 3.2.10
backport #8616, quote column names in generated fixture files

Conflicts:

	railties/CHANGELOG.md
	railties/lib/rails/generators/test_unit/model/model_generator.rb
	railties/lib/rails/generators/test_unit/model/templates/fixtures.yml
	railties/test/generators/model_generator_test.rb
Merge pull request #8618 from senny/backport_8612

backport #8616, quote column names in generated fixture files
Fix `validates_presence_of` with `:allow_nil` or `:allow_blank` options.

Fix #8621

[Colin Kelley + Rafael Mendonça França]
Revert "Fix `validates_presence_of` with `:allow_nil` or `:allow_blank` options."

This reverts commit 93366c7c913bf0883f140fa782d3e198593477be.

REASON: This is backward incompatible. Also this behavior is documented
on the guides.
backport #8662, charset should not be appended for `head` responses

      1) Failure:
    test_head_created_with_image_png_content_type(RenderTest) [test/controller/render_test.rb:1238]:
    Expected: "image/png"
      Actual: "image/png; charset=utf-8"
Merge pull request #8665 from senny/8661_should_not_append_charset_if_already_present

backport #8662, charset should not be appended for `head` responses
Revert "Merge pull request #8665 from senny/8661_should_not_append_charset_if_already_present"

This reverts commit e48dc194231830f42f179704596b88215f062c23, reversing
changes made to d38c8caa48a732d41c7402a5e71deece4e313559.
removes the Ajax on Rails early draft

There was a few attempts at writing this guide, but we
never passed from the work in progress stage. In spite
of not being included in the table of contents, this
draft was still indexed by bots and showed up in searches.

Steve Klabnik has written "Working with JavaScript in Rails"
which is going to be released with Rails 4. So better get
rid of this altogether.
fix block.arity raise nil error when not given a block to "content_tag_for"
Merge pull request #8640 from jasl/3-2-stable

fix block.arity will raise nil error
Merge branch '3-2-stable' into 3-2-secmerge

* 3-2-stable:
  fix block.arity raise nil error when not given a block to "content_tag_for"
  removes the Ajax on Rails early draft
  Revert "Merge pull request #8665 from senny/8661_should_not_append_charset_if_already_present"
  backport #8662, charset should not be appended for `head` responses
  Revert "Fix `validates_presence_of` with `:allow_nil` or `:allow_blank` options."
  Fix `validates_presence_of` with `:allow_nil` or `:allow_blank` options.
  backport #8616, quote column names in generated fixture files
Improve CHANGELOG message [ci skip]