slapos_accounting: Ignore constraint on non-slapos related Invoices

See merge request !519

master/bt5/slapos_accounting/SkinTemplateItem/portal_skins/slapos_accounting/SaleInvoiceTransaction_isTotalPriceEqualAccounting.py

 invoice = context
 
+specialise = context.getSpecialiseValue(portal_type='Sale Trade Condition')
+if specialise is None or specialise.getSpecialiseValue() is None:
+  if not len(invoice.objectValues(portal_type="Invoice Line")):
+    # The trade model don't applies if the Trade Condition isn't attached to
+    # A business process
+    return True
+
+
+
 total_price = invoice.getTotalPrice()
 if invoice.getTotalPrice() < 0:
   # For a negative total is from the Reversal transactions

master/bt5/slapos_accounting/SkinTemplateItem/portal_skins/slapos_accounting/SaleInvoiceTransaction_isTradeModelCorrect.py

 specialise = context.getSpecialiseValue(portal_type='Sale Trade Condition')
-if specialise.getSpecialiseValue() is None:
+if specialise is None or specialise.getSpecialiseValue() is None:
   # The trade model don't applies if the Trade Condition isn't attached to 
   # A business process
   return True