Implement :null_session CSRF protection method

Allow passing block to deep_merge and deep_merge!

Hash#merge accepts block that you can use to customize how hash values
are merged. This change makes merge and deep_merge compatible.

Add boolean type conversion for AR::Store

Allow ActiveSupport::Deprecation features to be used by rails applications and library authors

It's further work on CSRF after 24594110.

The :null_session CSRF protection method provide an empty session during
request processing but doesn't reset it completely (as :reset_session
does).

ActiveSupport::Deprecation is now a class rather than a module. You can
get instance of ActiveSupport::Deprecation calling #instance method.

  ActiveSupport::Deprecation.instance

But when you need to get new object od ActiveSupport::Deprecation you
need to just call #new.

  @instance = ActiveSupport::Deprecation.new

Since you can create a new object, you can change the version and the
name of the library where the deprecator concerned.

  ActiveSupport::Deprecation.new('2.0', 'MyGem')

If you need use another deprecator instance you can select it in the
options of deprecate method.

  deprecate :method, :deprecator => deprecator_instance

Documentation has been updated.

test local deprecation

deprecator object

Test ActiveSupport::Deprecation when included

update ConnectionAdapter::Column#type_cast_code to be compatible with rails 3.2 branch

add --skip-ignore and --skip-keeps options to generators.

Users of other SCM's can now generate rails
apps that will add the "empty" directories to source control,
but will not have a useless .gitignore or mis-named .gitkeep
files.

* Change `rails new` and `rails plugin new` generators to name
  the `.gitkeep` as `.keep` in a more SCM-agnostic way.

* Change `--skip-git` option to only skip the `.gitignore` file
  and still generate the `.keep` files.

* Add `--skip-keeps` option to skip the `.keep` files.

It closes #2800.

In some circumstances engine was Arel::Table.engine which for separate
reasons was an ActiveRecord::Model::DeprecationProxy, which caused a
deprecation warning.

In any case, we want the actual model class here, since we want to use
it to infer information about associations.

Previously the reflection would be looked up on the wrong class. However
the test passed because the examples referred back to themselves.

Convert model name to foreign key in queries

Update documentation for CollectionProxy [ci skip]

default is the SynchronousQueue.

We don't need to rely on rails/queueing in Action Pack tests

This allow the users to do:

    config.action_mailer.queue = MyQueue.new

and

    class UsersMailer < ActionMailer::Base
      self.queue = MyQueue.new
    end

We should not let the users use the ThreadedConsumer without know about
the risks

Add docs to inheritance_column method, explaining how to override it
to be able to use the "type" column without STI [ci skip]

single-table inheritance by overriding it in your ActiveRecord
Model.

Fixed support for DATABASE_URL for rake db tasks

Fix build Rails.queue

Remove '.rb' from require call

warning removed.

see 34b23e71

1. Unused variable
2. possibly useless use of a variable in 
void context

- added tests to confirm establish_connection uses DATABASE_URL and
  Rails.env correctly even when no arguments are passed in.
- updated rake db tasks to support DATABASE_URL, and added tests to
  confirm correct behavior for these rake tasks.  (Removed
  establish_connection call from some tasks since in those cases
  the :environment task already made sure the function would be called)
- updated Resolver so that when it resolves the database url, it
  removes hash values with empty strings from the config spec (e.g.
  to support connection to postgresql when no username is specified).

ConnectionPool, unify exceptions, ConnectionTimeoutError

Allows you to specify the model association key in a belongs_to
relationship instead of the foreign key.

The following queries are now equivalent:

Post.where(:author_id => Author.first)
Post.where(:author => Author.first)

PriceEstimate.where(:estimate_of_type => 'Treasure', :estimate_of_id => treasure)
PriceEstimate.where(:estimate_of => treasure)

Use mysqldump native commands when rake db:structure:dump. Closes #5547
Fixes database tasks config to use encoding instead of charset.