Add sanitize gem, change ISBN format to string
Add goodreadscover column to book table. Add ability see goodreadscover on show page after create new book
New Book link is not in table header on top left
Add else if statement to index show to allow showing of goodreadscover if present. Still need check for conflicts betw user uploaded picture and goodreadscover - want user uploaded pic to have priority
Modify books#index to allow current user to see and edit only their list of books