Added a route to show the user a form to edit a picture.
Defined edit_picture_form action.
Made edit_picture_form view template. The heading still needs the ID number of the requested picture.
Set up the @pic_id instance variable in the action using the dynamic route segment.
Copied the form HTML from the new action, added hardcoded default values for the input fields.
Inserted embedded ruby to replace hardcoded default values with dynamic data from the database. The @pic variable still doesn't exist.
Set up the @pic instance variable in the action by asking the Picture table for the appropriate row.