ActionMetaclass.__new__() creates a class object twice. At first,
it uses DeclarativeFieldsMetaclass.__new__() only to get a side effect
of gathering form fields to base_fields, and then it uses type.__new__()
to create the resulting class object. Dropping the first created class
object results in ignoring all that DeclarativeFieldsMetaclass.__new__()
does with it (currently, it adds a 'media' attribute).
This change uses the class object returned by
DeclarativeFieldsMetaclass.__new__() adding Meta options to it,
thereby fixing the issue.
Change-Id: Ia4ee0e7187846ea13c04505cbbe7b999c2044871
0e5179ac33