Reinstate explicit active_support/test_case require since console_app interacts with a non-autoloaded constant

Signed-off-by: NMichael Koziarski <michael@koziarski.com>

Stop featuring ActiveSupport::TestCase.use_instantiated_fixtures and ActiveSupport::TestCase.use_transactional_fixtures as likely-to-change settings in test/test_helper.rb -- they are not and their values are already set in test_help.rb [DHH]

Removed config/initializers/new_rails_defaults.rb as all frameworks now follow the settings from it [DHH]

Changed ActiveRecord::Base.store_full_sti_class to be true by default reflecting the previously announced Rails 3 default [DHH]

ActiveSupport.escape_html_entities_in_json from true to false to match previously announced Rails 3 defaults [DHH]

Added that ActionController::Base now does helper :all instead of relying on the default ApplicationController in Rails to do it [DHH]

Add notifications to ActionDispatch::ShowExceptions, this can be used as hooks for plugins like ExceptionNotifier.