Assignment completed

I started from scratch, so the versions of gems might slightly differ.  Minor modifications were made to the layout, including a home link and a "my links" link in the sidebar.  Only registered users can leave comments or submit links, but any viewers can see every link and comment.  Only the users that submitted a link or a comment can delete them.  Deleting a link also deletes all comments associated with the link from the database.  Users can upvote or downvote a comment as many times as they wish, there is no limit.  Link scores are based on cumulative comment scores.  This was tested mainly with integration tests.