The comparison between `Relation` and `CollectionProxy` should be consistent.

Example:

    author.posts == Post.where(author_id: author.id)
    # => true
      Post.where(author_id: author.id) == author.posts
    # => true

Fixes #13506
Make the comparison between 'Relation' and 'AssociationRelation'
consistent.
Ensure that the comparison between 'CollectionProxy' and 'AssociationRelation' is consistent.
CollectionHelpers now accepts a readonly option
Move tests for deep_dup and duplicable to object directory
Add a changelog entry for #14546 [ci skip]
Update documentation to use Rails.application instead

References to ``AppName::Application` removed in favour of ``Rails.application``
as generated with a new rails 4.1 app.

[ci skip]
Merge pull request #14727 from robin850/patch-17

Add a changelog entry for #14546 [ci skip]
Merge pull request #14718 from mcmorgan/update-documentation-to-match-generated-config

Update documentation to use Rails.application instead
Merge pull request #14722 from maurogeorge/mg-readonly-collection

CollectionHelpers now accepts a readonly option
Merge pull request #14726 from akshay-vishnoi/structural-change

Move tests for deep_dup and duplicable to object directory
Merge pull request #14592 from laurocaetano/equality_between_relation_and_collection_proxy

The comparison between `Relation` and `CollectionProxy` should be consistent.

Conflicts:
	activerecord/CHANGELOG.md