Added migration for Comments. Added Comments model.
Started adding the comments functionality. First created the view in the 'bookmark' show.html.erb.
Added updates to the bookmarks_controller for comments functionality
Added routes for comments. Added `create` at comments_controller.rb
Comments work! I should remove the extra empy list item at bookmarks/show
Added unformated menu to view-edit-delete comments. No functionality is
implemented yet.