generate comment model
add relation to many comments in post model
add comments as nested resource of posts
generate comments controller
add comment form in post/show view
add create action to comments controller
add comments listing to posts/show view
add partial for comment representation
edit posts/show view to use comment partial in comments listing
add partial for new comment form
edit posts/show to use partial for comments adding
add link to delete comment in comment representation partial
add destroy action to comments controller
edit post model to destroy nested resources
add authentification for CRUD actions in posts controller
add authentification for destroy action in comments controller