Do not perform 3D-secure enrolment check for AMEX

[davidduffett]

American Express does have it's own version of 3D-Secure (they call it SafeKey), however some merchants will not have this enabled on their DataCash accounts.

If it is not enabled, performing a 3D-Secure enrolment check, followed by authorisation just lengthens the payment process.

Provide a configuration option which will disable 3D-Secure enrolment checks for AMEX cards. If this option is enabled, it should authorise the transaction directly, rather than the 2-step enrolment check then authorise.