Gravity Forms Authorize.Net Addon 2.8.1

- Fixed a fatal error which could occur if the subscription object was not returned by the gform_authorizenet_subscription_pre_create or gform_authorizenet_before_start_subscription filters.

- Added support for Gravity Forms 2.3.
- Added "Automatic Retry is turned on in my Authorize.Net account" checkbox to Settings Page. This feature is required for ARB.
- Added additional error messages.
- Updated "Override Default Settings" so it can be translated
- Fixed an issue with logging a message when the error_message array in the response object was empty.
- Fixed strings for translations
- Fixed a test description appearing on the add-on settings page with Gravity Forms 2.2+.

- Fixed a test description appearing on the add-on settings page with Gravity Forms 2.2+.