Added slug field to Book Model
Modified BookAdmin class
Added south to installed apps
Added migrations folder
Added get_absolute_url to Book Model
Added slug for book url
Modified book link in books_by_pub.html
Modified book link in list_of_books.html
Added slug field for Publisher model and added get_absoulte_url function
Modified PublisherAdmin class
Modified publisher urlconf
Modified publisher view
Modified link in publishers.html
Added slug field for publisher Model