Add User model and controller with login and session token generation support
Remove unnecessary #new method from UsersController
Add sessions controller and corresponding new view (i.e., login page)
Remove static index.html page
Change Cat new view to persist values in case of error
Add ApplicationController#authenticate (for user authentication/session token storage)
Add CSRF protection to all forms
Add user_id column to cats table and corresponding associations
Update seeds file with users and cats' users_ids
Prevent unauthorized editing of cats
Prevent unauthorized authorization/denial of cat rental requests