Improve js written for guides

* Stop using unnecessary global variable
* Use function defined by jQuery for simplicity
* Fix event listner for "more info button" to handle
  event on resize browser
Add few information about missing steps [ci skip]

Add some deprecations previously note covered such as the confirm
option for the link_to helper or options which aren't needed anymore

Also add a mention about the config.assets.js_compressor option.
Document where `column` param gets utilized in `substitute_at`.
Use helper method to get ENV['CONTENT_LENGTH']
Use Request#raw_post instead Request#body

In order to get raw_post to be not empty after
ParamsParser#parse_formatted_parameters,
added rewinding of body stream input on parsing json params.

Closes #11345
cache.exists? should return true/false
Explicitly test for true and false.
Creating a class for carrying out rails commands.

This class encapsulates a lot of logic that wasn't very object oriented.
Helper methods have been created to try to make things more logical and
easy to read.
Added cursor pointer for 'More Ruby on Rails'

dropdown menu on guides page (which appear on small windows)
[ci skip]
Fix 2 grammatical errors/typos in Active Record Basics guide. [ci skip]
Merge pull request #11363 from dpdawson/master

Fix 2 grammatical errors/typos in Active Record Basics guide. [ci skip]
handle notes in *.sass files
Merge pull request #11367 from artemeff/sass_in_notes

handle notes in *.sass files
Merge pull request #11355 from wangjohn/class_for_rails_commands

Creating a class for carrying out rails commands.
Fixed broken link of Travis CI for rails and added full path
refactor to_sql so it does not depend on the to_sql implementation of
the connection
Fix a grammatical error/typo in Active Record Migrations guide. [ci skip]
Merge pull request #11370 from dpdawson/master

Fix a grammatical error/typo in Active Record Migrations guide. [ci skip]
actionview should be able to install using install.rb [ci skip]
Fixed broken rake task for update_version [ci skip]

Also added actionview to update version rake task