Simplify code in AS json encoder
replace regexp global in #url_for
Fix file name in document [ci skip]

This file was renamed in c8a25386d.
Fixing the examples for button_to

The examples do not generate the output they intend to due to not explicitly declaring the hash separations. This causes it to be treated as one parameter instead of the intended two parameters.
Change Class#subclasses doc example
Add ActiveRecord.count documentation when used on group relations
Add documentation for ActiveRecord.select when use strings as arguments
Add example for ActiveRecord::Base.group using a string as argument
Add example for ActiveRecord::Base.joins using a string as argument
Validations guide: validates_with init clarification.

As discussed with @josevalim on Ruby Rogues Parley.
Clarify ActiveModel::Validator initialization in docs.

As discussed with @josevalim on Ruby Rogues Parley.
Fix CoffeeScript example

`a[data-color]` is not used in example html.
Fix supported ruby version for Rails 4
Added notice message for destroy method in scaffold
Merge pull request #9233 from rahul100885/master

Added notice message for destroy method in scaffold
the `:controller` option for routes can contain numbers. closes #9231.
Merge pull request #9234 from senny/9231_no_numbers_in_route_namespaces_allowed

The `:controller` option for routes can contain numbers. closes #9231.
Prefer Ruby 2.0; require 1.9.3+
Improve img alt attribute for screen readers

Currently, the img_alt method in ActionView keeps underscores
in the alt attribute. Because underscores are pronounced in
Apple's VoiceOver Utility, this has serious implications for
accessibility. This patch makes underscored or hyphenated file
names (both common in projects) read more naturally in screen
readers by replacing them with spaces. See method documentation
for details.

Added documentation to image_alt method
added compress options for gzip

added test for compress options of gzip

update changelog