Custom parameter support in all supported gateways.

[phpmathan]

Adding support to send custom parameters.

send() method changed to send(array $datas = array(), $doMerge = true) to accept custom parameters.

use Omnipay\Common\GatewayFactory;

$gateway = GatewayFactory::create($gatewayName);
$gateway->initialize($gatewaySettings);

$defaultParams = array();
$request = $gateway->authorize($defaultParams);

$params = $request->getData();
$params['custom'] = 'value';

$response = $request->send($params, false);

[amacneil]

I see the use case, but I don't particularly like this API, passing extra parameters to send() like that. Open to discussion though.

I think I'd prefer some sort of sendData() method, which was called internally by send(), e.g.:

function send()
{
    $data = $this->getData();
    return $this->sendData($data);
}

function sendData($data)
{
    // gateway implements this method
}

[antranapp]

Any suggestion for passing custom parameters to the gateway. I also want to use mobile express checkout for paypal and need to pass a parameter to ExpressAuthorizeResponse to be able to choose the correct command "_express-checkout-mobile" for the redirection.

[amacneil]

Fixed in #162