remove cruft and improve pod as per #134

* remove cruft and improve pod for Message result class as per #134.
* remove cruft and improve pod for MessageType result class as per #134.
* remove cruft and improve pod for Order result class as per #134.
* remove cruft and improve pod for OrderComment  result class as per #134.
* remove cruft and improve pod for Product result class as per #134.
* remove cruft and improve pod for ProductReview result class as per #134.
is_nullable not needed here