For QBD an address may NOT be provided and a customer can be created
(no 'Addresses' XML node in POST request). If
an address is provided it must NOT be empty. See discussion here
https://github.com/ruckus/quickeebooks/pull/91
Merge pull request #125 from minimul/cannot-send-empty-address-qbd

For QBD an address may NOT be provided and a customer can be created