Fix human attribute_name to handle deeply nested attributes

True, False, and Nil should be represented in as_json as themselves.

[Guides] refactor rakefile to have a :guides namespace and a task that shows help

(Try again) Fix #5847 and #4045.

JRuby return different Array for module contents.

Test was failing against JRuby. 

It loads like [Constant3 Constant1]

Exceptions like Interrupt & NoMemoryError should not be rescued in tests.

update Gemfile template to 1.9 hash syntax

Decoupling ActiveSupport from ActionView

Add tests to delete by fixnum or string id with has many through associations

Merge commit 6f1d9d00

Some of these requires are now only necessary in
ActiveSupport::NumberHelper. Add hash/keys require due to symbolize_keys
usage in number helpers. Also remove some whitespaces.

Closes #6414

Add Changelog entry. Closes #4003

Add support for CollectionAssociation#delete by Fixnum or String

Refactor number helpers output with safety handling to call float
parsing only once. Also remove 'erb' require.

I found the next issue between CollectionAssociation `delete`
and `destroy`.

    class Person < ActiveRecord::Base
      has_many :pets
    end

    person.pets.destroy(1)
    # => OK, returns the destroyed object

    person.pets.destroy("2")
    # => OK, returns the destroyed object

    person.pets.delete(1)
    # => ActiveRecord::AssociationTypeMismatch

    person.pets.delete("2")
    # => ActiveRecord::AssociationTypeMismatch

Adding support for deleting with a fixnum or string like
`destroy` method.

Neither Test::Unit nor MiniTest rescue exceptions like Interrupt or
NoMemoryError, but ActiveSupport::Testing::SetupAndTeardown#run which
overrides MiniTest::Unit::TestCase#run rescues them.

Rescuing an Interrupt exception is annoying, because it means when you
are running a lot of tests e.g. when running one of the rake test tasks,
you cannot break out using ctrl-C.

Rescuing exceptions like NoMemoryError is foolish, because the most
sensible thing to happen is for the process to terminate as soon as
possible.

This solution probably needs some finessing e.g. I'm not clear whether
the assumption is that only MiniTest is supported. Also early versions
of MiniTest did not have this behaviour. However, hopefully it's a
start.

Integrating with Test::Unit & MiniTest has always been a pain. It would
be great if both of them provided sensible extension points for the kind
of things that both Rails and Mocha want to do.

[guides] guides:generate:kindle is the new interface to generate .mobi file instead of using KINDLE=1

[guides] get rid of any reference to the generator script since rake tasks are now the new interface

ActiveSupport require and dependencies

Use ActiveSupport::Multibyte::Chars.new instead of String#mb_chars.
It allows to use ActiveSupport::Multibyte::Chars without requiring
String multibyte core extension.

AS::Multibyte are no longer required by access and filters string
core extensions.

Don't enable validations when passing false hash values to ActiveModel.validates

Passing a falsey option value for a validator currently causes that validator to
be enabled, just like "true":

    ActiveModel.validates :foo, :presence => false

This is rather counterintuitive, and makes it inconvenient to wrap `validates` in
methods which may conditionally enable different validators.

As an example, one is currently forced to write:

      def has_slug(source_field, options={:unique => true})
        slugger = Proc.new { |r| r[:slug] = self.class.sluggify(r[source_field]) if r[:slug].blank? }
        before_validation slugger
        validations = { :presence => true, :slug => true }
        if options[:unique]
          validations[:uniqueness] = true
        end
        validates :slug, validations
      end

because the following reasonable-looking alternative fails to work as expected:

      def has_slug(source_field, options={:unique => true})
        slugger = Proc.new { |r| r[:slug] = self.class.sluggify(r[source_field]) if r[:slug].blank? }
        before_validation slugger
        validates :slug, :presence => true, :slug => true, :uniqueness => options[:unique]
      end

(This commit includes a test, and all activemodel and activerecord tests pass as before.)

Fix handling of negative zero in number_to_currency