missing require in buffered logger

Add config.file_watcher so developers can provide their own watchers (for instance, hooking on fsevents).

commented whitelist mode enforcement for mass assignment

missing require in activesupport test

This reverts commit c2e3ce8d.

Conflicts:

	railties/lib/rails/application/configuration.rb
	railties/lib/rails/application/finisher.rb
	railties/lib/rails/engine.rb

Fixes #3957

Use rubygems https endpoint for the Gemfile on new apps

Include TagHelper but don't explicitly require it

Allow autoloading to work as intended and avoid multiple requires.

Add ActiveSupport::Cache::NullStore for testing and development

This can be turned off by setting `config.reload_classes_only_on_change` to false.

Extensions like Active Record should add their respective files like db/schema.rb and db/structure.sql to `config.watchable_files` if they want their changes to affect classes reloading.

Thanks to https://github.com/paneq/active_reload and Pastorino for the inspiration. <3

Add ActiveSupport::Cache::NullStore to expose caching interface without actually caching for development and test environments.

Use HTTPS rubygems source

Fix #3365. Default config.relative_url_root to ENV["RAILS_RELATIVE_URL_ROOT"].