Add session_token
Add session methods
Generate UsersController with #new and #create
Generate SessionsController
Add Session #new, #create, #destroy
SessionsHelper from NewAuthDemo
Memoize current_user
Include SessionsHelper in ApplicationController
Add basic User views
Add sign-in view
Add users and sessions routes
Make :password attr_accessible
Make :session a singular resource
Remove default index.html
Generate and migrate Bill model
Add Bill owner association
Create and migrate BillSplit model
Add bill and debtor associations to BillSplit
Add bill_splits association to Bill
Rename users factory