Payum/PayumBundle — pull request #220 by aitboudad (2014-12-28 10:25:44+00:00)
Title: [Omnipay] allow user to add custom gateway.

Hi,
the current implementation doesn't allow to add unofficial gateway, I think we should find a way to add custom gateway.
The simplest way to solve this is to allow setting full class in param 'type' , here is an example:

```yaml
payum:
contexts:
paypal:
omnipay:
type: \Omnipay\PaypalRest\Gateway
...
```