added simplecov
don't make a round-trip to the server just to get the content (a.k.a. description)
clean up sessions; simplify current_user functionality
we don't support new comments on their own page, you can add them right from the index page
don't use instance vars when unnecessary; simplify comment creation code
don't use instance variables unnecessarily; handle the case of editing anonymous topics
make the logged_in? and current_user methods available to the controllers