Added route and stub controller/view for sessions
Added tests for sign in authentication
Added view for sign in.
Handle sign-in with incorrect information, show error message.
Added SessionsHelper to controllers, and SessionsController now calls (not-yet-implemented) sign_in method
Added remember_token to user model in db, including test
Create a remember_token before saving user
Added functions to SessionsHelper for signing in and accessing sign_in status.
Added view and helper to show different browser links for signed in users.
Automatically sign in users after they sign up.
Added user signout functionality.
Change sign_in form to use form_tag instead of form_for.