Article manager

• Let users register with a username and a password (non-logged in users only),
• Let users log in with a username and a password (non-logged in users only),
• Let users log out (logged in users only),
• Let users create new articles (logged in users only),
• Display the list of all articles on the home page (for all users), and
• Display a single article on its own page (for all users).