change format example to read better when rendered with full_messages

The capital O was awkward and the validation wouldn't read "right" to the user.
Moving add_column_options! up to SchemaCreation

removed two instances of add_column_options! from abstract_mysql_adapter

reworked rename_column_sql to remove add_column_options from schema_statements

changed to use new hash syntax.
Add missing nsec test for 17f5d8e
Merge pull request #10425 from ranjaykrishna/push_add_column_options_to_schema_creation

Push add column options to schema creation
Ambiguous reflections are on :through relationships are no longer supported.
For example, you need to change this:

  class Author < ActiveRecord::Base
    has_many :posts
    has_many :taggings, :through => :posts
  end

  class Post < ActiveRecord::Base
    has_one :tagging
    has_many :taggings
  end

  class Tagging < ActiveRecord::Base
  end

To this:

  class Author < ActiveRecord::Base
    has_many :posts
    has_many :taggings, :through => :posts, :source => :tagging
  end

  class Post < ActiveRecord::Base
    has_one :tagging
    has_many :taggings
  end

  class Tagging < ActiveRecord::Base
  end
Merge pull request #10890 from buytruckload/master

update format validation documetation
clean up ivar assignment
push ambiguous reflection warning down to reflection name calculation
active_record should always be set. Do or do not, there is no try