Fix dataformat according to feedback

README.md

@@ -32,7 +32,6 @@ transactions = [Transaction.from_dict({
 })]
 
 vouchers = [Voucher.from_dict({
-    "batchid": 1,
     "exref": 3,
     "voucherno": 4,
     "transactions": transactions
@@ -44,7 +43,6 @@ batch = Batch.from_dict({
     "period": 3,
     "interface": 4,
     "vouchertype": 5,
-    "batchid_interface": 6,
     "vouchers": vouchers
 })
 

tests/fixtures/batch_fail_fixture.json

@@ -4,8 +4,7 @@
     "batchid": 54,
     "period": 1,
     "interface": 1,
-    "vouchertype": 1,
-    "batchid_interface": 1
+    "vouchertype": 1
   },
   "vouchers": [
     {

tests/fixtures/batch_fixture.json

@@ -4,6 +4,5 @@
   "period": 3,
   "interface": 4,
   "vouchertype": 5,
-  "batchid_interface": 6,
   "vouchers": []
 }

tests/fixtures/batch_with_voucher_fixture.json

@@ -4,7 +4,6 @@
   "period": 1,
   "interface": 1,
   "vouchertype": 1,
-  "batchid_interface": 1,
   "vouchers": [
     {
       "exref": 1,

tests/fixtures/voucher_fixture.json

 {
-  "batchid": 1,
   "exref": 3,
   "voucherno": 4,
   "transactions": [