Rename the old CORE Customer model, to CustData

it now has a new Customer model, so we use that where we can

rattail_corepos/importing/corepos/api.py

@@ -102,7 +102,7 @@ class CustomerImporter(FromCOREPOSAPI, importing.model.CustomerImporter):
             if customer:
                 customers[dbcust.card_number] = customer
             else:
-                logger = log.warning if dbcust.person_number == 1 else log.debug
+                logger = log.warning if dbcust.account_holder else log.debug
                 logger("could not fetch customer from CORE API: %s",
                        dbcust.card_number)