fix set descendant class
unit test
fixed file description
inverted actual and expected values
Update runtime/lib/om/BaseObject.php

fixed typo
Merge pull request #575 from staabm/patch-1

Update runtime/lib/om/BaseObject.php
Merge pull request #569 from nibsirahsieu/fix_set_descendant_class

fix set descendant class
Merge remote branch 'upstream/master'