Publish a Chapter to an existing Story

[sorachung]

GIVEN user is authenticated
WHEN user selects the “Post” menu option then the “Add to Existing Story” suboption
THEN the user should be redirected to the user profiles subpage showing all of the current user’s stories with an Add Chapter button

WHEN the user clicks Add Chapter on one of the stories
THEN the user should be redirected to the Add Chapter form

GIVEN the user has filled out the fields
WHEN they click the Publish button
THEN a new Chapter should be saved to the database
AND the user should be redirected to the latest chapter of the story