Unit Testing Code Snippet

I have added a note to inform the user that they will need to mock out the getAlbum() method of AlbumTable as you get the following error otherwise:

1) AlbumTest\Controller\AlbumControllerTest::testEditActionRedirectsAfterValidPost
Zend\Form\Exception\InvalidArgumentException: Zend\Form\Fieldset::setObject expects an object argument; received ""
Merge pull request #1143