Make the SessionsHelper module available to all controllers
Add :remember_token column to Users
Set the remember_token before saving the User

* The database stores the encrypted version of the token
Add helper methods for sessions

* Handle tokens when signing in
* Set and get the current logged in user
Addd check for signed_in?
Expand navbar to display links using signin status

Also include the javascript libraries to make the dropdown lists
work correctly.
Sign in the user after signup
Allow a user to sign out (destroy the sesion)
Add cucumber-rails and database_cleaner gems
Generate cucumber:install
Add cucumber specs for signin