Escalate missing error when :raise is true in translate helper, fix regression introduced by security fix.

Before ec16ba75,
ActionView::Helpers::TranslationHelper#translate has raised errors with
specifying options[:raise] to true.

This should work by this fix:

     begin
       t(:"translations.missing", raise: true)
     rescue I18n::MissingTranslationData
       p :hello!
     end

update guides to new version of rails 3.2.x [ci skip]

Fixed json_escape (again)

Expanded test coverage for html_escape and json_escape

removed duplicate test case

remove nil in NullType#ref.

Return Nil is implicit in a method and this syntax is used in the others
classes

Formatting, capitalization, and punctuation fixes [ci skip]

Second try on this commit.

TextHelper#simple_format attempts to call undefined raw method

Fix AR#method_missing re-dispatching into overwritten attribute methods

Conflicts:
	activerecord/lib/active_record/attribute_methods.rb

Now users have to explicit mark the unit as safe if they trust it.

Closes #13161

Conflicts:
	actionpack/lib/action_view/helpers/number_helper.rb
	actionpack/test/template/number_helper_i18n_test.rb

Follow up to #12958.

Install Spring preloader when generating new applications

Added JSON related items to the 4.1 release notes

Avoid one-liner conditionals when they are too big. Avoid concatenating
strings to build error messages. Improve messages a bit.

Action Pack Variants

By default, variants in the templates will be picked up if a variant is set
and there's a match. The format will be:

  app/views/projects/show.html.erb
  app/views/projects/show.html+tablet.erb
  app/views/projects/show.html+phone.erb

If request.variant = :tablet is set, we'll automatically be rendering the
html+tablet template.

In the controller, we can also tailer to the variants with this syntax:

  class ProjectsController < ActionController::Base
    def show
      respond_to do |format|
        format.html do |html|
          @stars = @project.stars

          html.tablet { @notifications = @project.notifications }
          html.phone  { @chat_heads    = @project.chat_heads }
        end

        format.js
        format.atom
      end
    end
  end

The variant itself is nil by default, but can be set in before filters, like
so:

  class ApplicationController < ActionController::Base
    before_action do
      if request.user_agent =~ /iPad/
        request.variant = :tablet
      end
    end
  end

This is modeled loosely on custom mime types, but it's specifically not
intended to be used together. If you're going to make a custom mime type,
you don't need a variant. Variants are for variations on a single mime
types.