Add logic in create action of Credentials controller to sign up new users
Add logic in create action of Sessions controller for user login
Add helper method to ApplicationController
-the helper method checks whether the user is logged in and displays
the appropriate link
Add Dashboard controller
Add WelcomeMailer
-sends an email containing a validation link to new signups
-change data model. create one-to-many associations instead of
embedding documents
Add welcome_email.text.erb
-delete welcome_email.html.erb
Add a validation code and a code expiration date to new users
-edit the validation link in the welcome email
Add Users controller
-the edit action will render a form to create new user account