Rename get_business_object -> get_object_xml

More consistent with `update_object_xml`. Also experimentally remove the
`self.class.object_name` filter from BusinessObject#get_field_node and
BusinessObject#to_hash (since this will be unset if the BusinessObject
base class is used directly, and I'm assuming XML documents will likely
only contain one BusinessObject element).
Add verbose_logging option

This seems the easiest way to enable/disable logging in Savon 2.