fixes :test option passed to ActiveMerchant::Billing::AuthorizeNetGateway to reflect server setting

>> Well the preference server still needs to be added for this payment method it's only been added to non cim gateway.

 I added the :server as a preference for this payment method. 

>>This looks to me like not having 'live' as the value for the new server preference that has no default will result in the preferences[:test] being set to true, which I thought it was what decides whether to hit the test or production server

That is a correct observation. You are correct to be cautious about any impact to anyone's existing setup and I understand the caution. It is my understanding that the correct settings for a live, production environment are the string "live" (4 character string) in the :server preference, and Test Mode set to off.

If someone is running  a store and does not have that in the Production environment, this change will make the transactions hit the sandbox environment, that is correct.

We could

1)  change the the 'live' whitelist to a 'test' blacklist, and make any string != "test" hit the production server
2) make either "live" or empty string "" hit the live server, everything else hit the test server
3) Raise an exception if you have neither "live" nor "test" as the server preference. 

Personally I would opt for #3 with a loud warning sign to anyone upgrading alerting them that they must explicitly set their server setting to "live" or "test".