added devise to app, adds user authentication

Here is the routes

          Prefix Verb   URI Pattern                                                          Controller#Action
             new_user_session GET    /users/sign_in(.:format)                                             devise/sessions#new
                 user_session POST   /users/sign_in(.:format)                                             devise/sessions#create
         destroy_user_session DELETE /users/sign_out(.:format)                                            devise/sessions#destroy
                user_password POST   /users/password(.:format)                                            devise/passwords#create
            new_user_password GET    /users/password/new(.:format)                                        devise/passwords#new
           edit_user_password GET    /users/password/edit(.:format)                                       devise/passwords#edit
                              PATCH  /users/password(.:format)                                            devise/passwords#update
                              PUT    /users/password(.:format)                                            devise/passwords#update
     cancel_user_registration GET    /users/cancel(.:format)                                              devise/registrations#cancel
            user_registration POST   /users(.:format)                                                     devise/registrations#create
        new_user_registration GET    /users/sign_up(.:format)                                             devise/registrations#new
       edit_user_registration GET    /users/edit(.:format)                                                devise/registrations#edit
                              PATCH  /users(.:format)                                                     devise/registrations#update
                              PUT    /users(.:format)                                                     devise/registrations#update
                              DELETE /users(.:format)                                                     devise/registrations#destroy