Complete user session created

Hoepfully it's complete. I don't know how to allow a session creation on the user welcome page. i assume some has_a relationship between session and user will have to exist. Anyway for now, I just used a new session controller action, and removed the feature to sign in on login page. Let me know what you think; test it.
I also added a navigation bar. I don't fully understand your css arrangement so I didn't style the navigation bar. You will notice it alternates between "login" and "logout" depending on if user is logged in or not