Notify Controller doUnsafeAction doesn't resolve gateway name parameter

[ilCleme]

As route payum_notify_do_unsafe describe, this controller should recieve a gateway_name parameter, to retrive the right gateway from payum. Instead this method receive a Request object and cannot get the right parameter.

The test can be done easily, call route('payum_notify_do_unsafe', ['gateway_name' => 'gateway-test']) via HTTP, throws a InvalidArgumentException with messagge Gateway "" does not exist. instead of Gateway "gateway-test" does not exist.

The PR #54 fix the issue.