rails authentication with devise

devise-auth-for-rails

updated: 31/03/2019 with rails 5.2

add `gem 'devise'` to gemfile
bundle install

rails g devise:install

Ensure you have defined default url options in your environments files. Open up config/environments/development.rb and add this line:

  ```config.action_mailer.default_url_options = { host: 'localhost', port: 3000 }```

Ensure the default route is settled in config/routes, for instance:
  ```root to home#index```
   
Ensure to have flash messages in app/views/layouts/application.html.erb
  ```rails g devise user
     rails db:migrate```