Added a sessions controller
Added sign in/out routes, rudimentary tests for the sign in page, and made a simplistic sign in page.
Added tests for valid/invalid login
Added the sign in form to the sign in page.
Sign in form now behaves correctly on invalid form submission.
Starting sign on session persistence.
Added the remember_token column to the user table and create it before a user is created.
Added a sign in function to the sessions helper that creates a new token and saves it in a browser cookie and updates the corresponding user attribute.
Updated the links in header to reflect whether the user is signed in or out. All tests pass.
Made sure users are signed on after registration.
Added sign out functionality.