Creates Comment model and associated files
Creates polymorphic commentable association for comment as well as belongs to user association
Adds comments to User and Petition models as commentable
Adds authored_comments association on user
Creates routes for creation and deletion of comments
Adds create and destroy methods to CommentsController
Adds helper and spec files for CommentsController
Creates a comments _list partial to render in User and Profile show views
Renders comments _list partial in User, Petition, and Me views
Removes left padding on headertext div in petition-show.css and adds a right margin to the image