Revert "Chapter 9"

This reverts commit 22824cbfd4baa5a3106d03178fc3d1303d794a8a.

Conflicts:
	app/assets/stylesheets/application.css
	app/controllers/comments_controller.rb
	app/helpers/application_helper.rb
	app/views/articles/index.html.erb
	app/views/articles/show.html.erb
	app/views/comments/_comment.html.erb
	app/views/comments/create.js.erb
	app/views/comments/destroy.js.erb
	app/views/comments/fail_create.js.erb
	app/views/comments/new.js.erb
	app/views/layouts/application.html.erb