slugify
Returns a unique slug for the item.
Example
b = Book.new
b.title = 'Darkly Dreaming Dexter'
b.slugify #=> "darkly-dreaming-dexter"
b.slugify("Dexter by Design") #=> "dexter-by-design"
b = Book.new
b.title = 'Darkly Dreaming Dexter'
b.slugify #=> "darkly-dreaming-dexter"
b.slugify("Dexter by Design") #=> "dexter-by-design"