Issue #13 Support user fields

See issue #13 for details.

Support symfony/property-access 4.x

Supports both ^3.2 and ^4.0 with no changes to functionality. See issue #10 for details.

Support notification signature validation

See issue #9

Also removed PHP 5.6 test support. PHP 7.x syntax used, though only in the acceptNotification handler for now.

Released as minor version, as sites not using the signature will fail until they either supply a signatureKey, or set the disableWebhookSignature flag - $gateway->setDisableWebhookSignature(true) - to suppress the assertion.

Support customerId

Issue #8 Support customerId, customerTaxId, and customerType when authorising a payment.

Fixed missing import

Fixed missing import. Thank you @ptuchik

Opaque Data as a Token

The pair of Opaque Data values can be supplied as a token parameter by joining them using a colon (:).

This provides a more consistent Omnipay API.

Webhook notifications support

Supports just the notifications, not the RESTful webhook management API.

Opaque data support

Opaque data support and more complete docs.

Tests have taken a back seat, as usual, due to time pressures. Any help would be appreciated.