Converts gateway settings from 3.1 format to 4.1, and sets active gateways. At the time of writing this, however, the only gateways created for 4.1 were Authorize.net AIM, Bank, Check, Invoice, Paypal Pro and Paypal Standard.
IMPORTANT: if an error is encountered, or everything is finished, this stage should update its status property accordingly. Note: it should not alter the count of items migrated. That is done in the public function that calls this. IMPORTANT: The count of items migrated should ONLY be less than $num_items_to_migrate when it's the last migration step, otherwise it should always return $num_items_to_migrate. (Eg, if we're migrating attendees rows from the database, and $num_items_to_migrate is set to 50, then we SHOULD actually migrate 50 rows,but at very least we MUST report/return 50 items migrated)
Methods inherited from EE_Data_Migration_Script_Stage
Methods inherited from EE_Data_Migration_Class_Base