Fix has_many assocation w/select load after create

Update test names and locations

Change the default test locations to avoid confusion around the common
testing terms "unit" and "functional".
Add new rake tasks for the new locations, while maintaining backwards
compatibility with the old rake tasks.

New testing locations are as follows:

    app/models -> test/models (was test/units)
    app/helpers -> test/helpers (was test/units/helpers)
    app/controllers -> test/controllers (was test/functional)
    app/mailers -> test/mailers (was test/functional)

Add missing entry in CHANGELOG about config.assets.cache change

Minor refactors in assets test

Rails.config doesn't exist, it should be Rails.application.config instead

The start of the week is a parameter nowadays, it is a little
confusing that we say here that we assume something about it.
Better to use "next" and "previous", which are clear regardless
of the concept of beginning of week.

Adds examples for the edge cases where the receiver is a
Monday or Sunday itself.

ActiveSupport core extensions guides update

remove unnecessary object/conversions file

Remove duplicate 'the' article in commented line

The sentence used to read "at the bottom of the the compiled file"

remove unused `expand_range_bind_variables` method

this method was not used, not documented and not tested.

Moving locale stuff from app.rb to an initializer.

Should use app.paths instead of specific path.

Rename "ActiveRecord::Fixtures" to "ActiveRecord::FixtureSet"

Update actionmailer with new hash syntax.

Just to make clear we don't accept this kind of pull request because it can invalidate a lot of pull requests.

I'm accepting this because Action Mailer has only two open pull requests.

Rename `ActiveRecord::Fixtures` class to `ActiveRecord::FixtureSet`.  Instances of this class normally hold a collection of fixtures (records) loaded either from a single YAML file, or from a file and a folder with the same name.  This change make the class name singular and makes the class easier to distinguish from the modules like `ActiveRecord::TestFixtures`, which operates on multiple fixture sets, or `DelegatingFixtures`, `::Fixtures`, etc., and from the class `ActiveRecord::Fixture`, which corresponds to a single fixture.

Fix warning: circular require considered harmful.