Map additional data from gateway response.
* added alter hooks to sf_donation to allow modules to change the mappable fields and final SF object
* Added functions to gm authorize.net to store the authorize.net response in an array and map the additional data to the object
* clearing uc credit cache at start of donation.php processing
CHANGELOG entries
Merge pull request #295 from JacksonRiver/6.x-jr-422-sync-additional-gateway-info

Create a system to enable the mapping of additional gateway response fields.