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.
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.
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]