Presented at RailsConf, April 2017
------------------- BREAKING CHANGES -------------------------
Change Action View ERB handler from Erubis to Erubi
https://github.com/rails/rails/pull/27757
Deprecate String options :if and :unless to set/skip callbacks
https://github.com/rails/rails/commit/0952552
Deprecate :action and :controller path parameters
https://github.com/rails/rails/pull/23980
------------------- ACTIVE RECORD -------------------------
Add ActiveRecord::Base. connection_pool.stat
https://github.com/rails/rails/pull/26988
Change default primary keys to BIGINT
https://github.com/rails/rails/pull/26266
Virtual column support for MySQL and MariaDB
https://github.com/rails/rails/commit/65bf1c6
Adds support for limits in batch processing
https://github.com/rails/rails/commit/451437c
------------------- ACTIVE SUPPORT -------------------------
Update Unicode version to 9.0.0
https://github.com/rails/rails/pull/27822
DateTime#change supports :usec and :nsec options
https://github.com/rails/rails/pull/28242
Add Duration#after and #before as alias for #since and #until
https://github.com/rails/rails/pull/27721
Introduce Module#delegate_missing_to
https://github.com/rails/rails/pull/23930
------------------- ACTION VIEW -------------------------
Add option :check_parameters to current_page?
https://github.com/rails/rails/pull/27549
New syntax for Action View’s tag helpers
https://github.com/rails/rails/pull/25543
Add form_with to unify form_tag and form_for
https://github.com/rails/rails/pull/26976
------------------- RAILTIES -------------------------
Display railtie class name in "rails initializers"
https://github.com/rails/rails/pull/25257
Added a shared section to config/secrets.yml
https://github.com/rails/rails/commit/e530534
Add encrypted secrets in config/secrets.yml.enc
https://github.com/rails/rails/pull/28038
Drop jQuery as a dependency and include rails-ujs
https://github.com/rails/rails/pull/27113
Add Yarn support in new apps using --yarn option
https://github.com/rails/rails/pull/26836
Basic --webpack delegation to new webpacker gem
https://github.com/rails/rails/pull/27288
------------------- ACTION PACK -------------------------
Capybara integration with Rails (AKA System Tests)
https://github.com/rails/rails/pull/26703
Custom URL helpers and polymorphic mapping
https://github.com/rails/rails/pull/23138
------------------- ACTIVE JOB -------------------------
Add retry_on/discard_on for better exception handling
https://github.com/rails/rails/pull/25991
------------------- ACTION MAILER -------------------------
Add parameterized invocation of mailers
https://github.com/rails/rails/pull/27825