Payment for Maestro Card on my Production apps is failing. Each time i keep getting ERROR:
"That payment method is unsupported. Please choose another one."

When I check `ActiveMerchant::Billing::AuthorizeNetGateway.supports?('maestro')`
It Retuns `false` always for `Maestro Cards`

So I forked it and add maestro as SupportedCard Types in AuthorizeNetGateway.
Also updated the corresponding test case which pass maestro credit card as well.

You can use the following test Maestro credit card  when testing your Authorize.net checkout:
Maestro: 6759649826438453