Gem versions, including security-related mail gem update (#3687)

* Update mail to version 2.6.6

* Update aws-sdk to version 2.9.37

* Update capybara to version 2.14.2

* Update oj to version 3.1.0

* Update sidekiq to version 5.0.2

* Update puma to version 3.9.1

* Update sanitize to version 4.5.0

* Update capistrano-rails to version 1.3.0