Prior to this commit, there isn't a good way of adding things like
default inline attachments to an email.  This Stack Overflow thread
shows people using hooks like the 'default' method in ActionMailer::Base
to call a Proc for message configuration:

http://stackoverflow.com/questions/5113121/rails-use-same-attachment-for-all-emails-using-layout

This has the unintended side effect of setting a message header, so it's not a good solution.

This pull request adds support for message modifications by including AbstractController:Callbacks
in ActionMailer::Base. It includes tests and documentation for the functionality
provided by including this module.

Fix comments about to_partial_path

configure how unverified request will be handled

Fix actionmailer tests broken by #4751a699

Change api_only to http_only and add MiddlewareStackProxy docs

[Carlos Antonio da Silva & Santiago Pastorino]

[Carlos Antonio da Silva & Santiago Pastorino]

Active model serialization :include returning string keys

Better syntax highlight :)

can be configured using `:with` option in `protect_from_forgery` method
or `request_forgery_protection_method` config option

possible values:
- :reset_session (default)
- :exception

new applications are generated with:

    protect_from_forgery :with => :exception

Use one system call whenever possible, group rake and Dir.chdir calls

In AR depths use &:to_i before :uniq to process mixed arrays likes ["1", 1] correct

Missing active_model/naming.rb dependency.

Fix my name in the CHANGELOG to follow the convention

Remove warning of unused variable

ActiveModel::Name constructor expects to be able to call #blank? on a
String but the core Object#blank? extension is never required.

Also add missing entries and use the formating convention

make active_connection? return true only if there is an open connection in use for the current thread. fixes #5330

Last commit message should not have said 'Rails 4' either

This reverts commit fd584a63.

Reason: This is not suitable for a Rails guide in my opinion.

refactor Hash#slice and Hash#extract!

Change the message string to use in  test case.

Update CHANGELOG to fix wrong extension.