Add validation to check for username presence and uniqueness
Add bcrypt gem for authentication
Refactor code to redirect to the users index after creating or updating a user and order users alphabetically
Add a flash notice when creating or updating a user
Add formatting to the new user form
Update users controller tests to reflect the validation and redirection changes
Update test fixtures to ensure there are no duplicate names
Add session and admin controllers
Add login form
Add login form and administrator index page
Refactor admin and session controllers