Fixed property types to reflect what Infusionsoft is sending

Found some issues while working with the code.

```
var invoice = infusionsoft.DataService.Query<Invoice>(q => q.Add(o => o.JobId, 123));
var invoicePayment = infusionsoft.DataService.Query<InvoicePayment>(q => q.Add(o => o.InvoiceId, invoice.Id));
var payment = infusionsoft.DataService.Query<Payment>(q => q.Add(o => o.Id, invoicePayment.PaymentId));
var charge = infusionsoft.DataService.Query<CCharge>(q => q.Add(o => o.PaymentId, payment.Id));
```