Store FlashHashes in the session as plain hashes rather than custom objects with unstable class names and instance variables.

Refactor FlashHash to take values for its ivars in the constructor, to pretty up FlashHash.from_session_value.

Remove stale comment on FlashHash: it is no longer Marshaled in the session so we can change its implementation.

Remove blank lines I introduced in controller/test_case.rb.

Unit tests for FlashHash#to_session_value.

Put in a compatibility layer to accept FlashHash serializations from Rails 3.0+.

Test that Rails 3.2 session flashes are correctly converted to the new format.

Remove code path for processing Rails 3.0 FlashHashes since they can no longer deserialize.

Fix session['flash'] deletion condition: it will never be empty?, it will either be nil or a hash with 'discard' and 'flashes' keys.
Fix broken link in Active Record Query Interface guide
cleanup, remove whitspace from railties CHANGELOG
require bundler groups to include rake-tasks in engines

If you generate a full engine, this will include rake tasks from
your gem under the `app` namespace. For example if you have a dependency
on `rspec-rails` in your engine's `gemspec`. You will get the task `app:spec`

Closes #8229
displaying error message(p tag was missing) and adding output as comment 
Merge pull request #8256 from nalwayaabhishek/master

Displaying error message if validation fail in examples (p tag was missing)
Merge pull request #8262 from senny/8229_correct_bundler_require_in_engines

require bundler groups to include rake-tasks in engines
Initialize accessors to remove some warnings in Ruby 2.0
Remove not needed begin..end from AR#save
Fix UpgradeSignatureToEncryptionCookieStore doc
Add UpgradeSignatureToEncryptionCookieStore to upgrading_ruby_on_rails guide
Explicit multipart messages respect :parts_order

As issue #7978, the order in which ActionMailer
sends multipart messages could be unintentionally
overwritten if a block is passed to the mail
method. This changes the mail method such that
:parts_order is always respected, regardless of
whether a block is passed to mail.
Merge pull request #8044 from nateberkopec/block_does_not_set_parts_order

Explicit multipart messages respect :parts_order
render every partial with a new `PartialRenderer`.

This resolves issues when rendering nested partials.
Previously the `PartialRenderer` was reused which led to
situations where the state of the renderer was reset.

Closes #8197
Merge pull request #8212 from senny/8197_make_render_in_spacer_template_work

render every partial with a new `PartialRenderer`.
Be a bit less conservative with mysql in adapter
Refactor request tests, remove #with_set method
Fix issue with params in url_for

With a "params" argument, the following error is raised:

    undefined method `reject!` for "":String
Correct the use of params options when given to url_for

Merge url for tests and add changelog entry for #8233.
Merge branch 'url-for-params'

Fix error when using a non-hash query argument named "params" in `url_for`.

Before:

    url_for(params: "") # => undefined method `reject!' for "":String

After:

    url_for(params: "") # => http://www.example.com?params=`

Closes #8233