RUBY ON RAILS CODING CHALLENGE | Generate a Rails app that allows a user to create, edit, update, and destroy (delete) users. *   Users should have first name, last name, and email address fields. First name is required. Email should be a valid email. Deploy this app to Heroku (a free *.herokuapp.com URL) so we can test it out live. If you breezed through this challenge, add extra features to this app (be creative). Be sure to paste the URL to your deployed app here.