added the postgresql database into the gemfile
modified the route inorder to make it work on heroku
moved the root route to the top to see whether it works on heroku
enabled user to register, need to style it up
changed the index page, removed the start-template css stylesheet, added a jumbotron-narrow stylesheet
transformed the css of user into sass format, added a bcrypt gem to secure password
removed some useless css files, using javascrit to do error handling of registration
secured the password
redesigned the layout
made the page title dynamic, using yield :title and provie(:title, "title")