Latest AVS Rules support PR breaks transactions without address

[jason-nabooki]

When PR #36 was merged in, it broke transactions that do not contain an address. Braintree doesn't require an address for a transaction but it does if you have AVS rules configured.

By default AVS rules are not configured so this can be replicated with a new Braintree sandbox account.

If you try to make a transaction without an address the Braintree API will reject it with the following error...

message=Addresses must have at least one field filled in

For more information on this error see https://developers.braintreepayments.com/reference/general/validation-errors/all/ruby#code-81801

@barrycarrjr