Activated first parameterized format test.

This is the test:

    classes = documentationtools.list_all_abjad_classes()
    @pytest.mark.parametrize('class_', classes)
    def test___format___01(class_):
        r'''All concrete classes have a storage format.
        '''

        if '_storage_format_specification' in dir(class_) and \
            not inspect.isabstract(class_):
            instance = class_()
            instance_format = format(instance, 'storage')
            assert isinstance(instance_format, str)
            assert not instance_format == ''

The test ensures that all concrete classes have a storage format.

The test also ensures that the storage format is not only an empty string.

All concrete classes now pass this test.