QuickBooks Payments 

WIP to integrate QuickBooks Payments.

Basic integration is complete, items remaining:
- [x] update integration to calculate OAuth signature given all token credentials
- [ ] remote tests for Quickbooks 
- [ ] unit tests 
- [x] implement some pattern for generating a GUID
 
sometimes you do, see the success method below, also the error is a litte more specific than what I wrote there :

```
The charge with id {0} processed, but the cvc check could not be validated. The merchant desired for this transaction to be refunded, but we were unsuccessful. The merchant must refund this transaction manually.Charge transactions with capture set to false can not be refunded.

{0} will be the transaction id.

```