remove duplicated require statements in AR test cases

Build failed with an error "invalid multibyte char (US-ASCII)" in these
files. Apparently, some UTF-8 char disguised as whitespace causes this.

Thanks @rafaelfranca

Offer instructions for pg gem when installed via Homebrew

Moving to new hash syntax

Conflicts:
	activerecord/lib/active_record/persistence.rb
	railties/lib/rails/generators/rails/resource_route/resource_route_generator.rb

This reverts commit 1c02b988.

This reverts commit 93b1ca8b.

Fix AS::Cache version upgrading bug

Remove old asset tag concatenation

Use sprockets, jammit, or some other asset bundler

Add missing CHANGELOG relating to addition of callbacks to mailers

Revert "Add changelog/release note entries for missing ActionMailer super feature related to inclusion of callbacks in mailers"

This reverts commit f16ec8c8.

Add changelog/release note entries for missing ActionMailer super feature related to inclusion of callbacks in mailers

warning fixed: ambiguous first argument; put parentheses or even spaces

fix typo in "The Rails Initialization Process"

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