Finish incomplete Rails 5.2 upgrade

The DLG project was upgraded to Rails 5.2 in July 2018 (e71556d2). I noticed that some of the configuration files associated with 5.2 are missing.

We need to: -Add the missing files/settings. Run: app:update

• Follow the advice in the Rails upgrade guide and release notes: https://guides.rubyonrails.org/upgrading_ruby_on_rails.html#upgrading-from-rails-5-1-to-rails-5-2
• Make sure test suite passes at this point and fix errors
• Go through config/initializers/new_framework_defaults.rb and flip each, one at a time while running the test suite in between.
• in config/application.rb, set config.load_defaults to 5.2
• remove config/initializers/new_framework_defaults.rb