Push notifications for Invoice transactions

[davidmcl]

Not that I'm personally using them yet, but I noticed that the "invoice" notification node doesn't seem to be covered in the push_notification.php code.

e.g., new_invoice_notification, closed_invoice_notification

They use account & invoice child-nodes.

Just thought I'd put it on the radar.

Thanks,
David

[drewish]

Thanks for the heads up. This was fixed in #159

[davidmcl]

Excellent timing - I was just about to start using them - thanks.

Cheers,
David