Fix for generated "The create view is rendered again with the correct model" condition in save

Currently, the generated spec will fail when ran against a domain class called board as follows ( after adding a property to the domain class ):

| Failure:  Test the save action correctly persists an instance(com.kanbanito.BoardControllerSpec)
|  Condition not satisfied:
model.board!= null
|     |    |
|     null false
[boardInstance:com.kanbanito.Board : (unsaved)]

the fix causes the line model.boardInstance to be generated instead of model.board, which then makes the test pass.