Modified UBL sample instances

Attached are my current copies of the UBL sample instances
originally prepared by Stephen Green.  Changes applied since PRD2
to make them validate against today's PRD3 schemas:

All .xml files:

 - Change all SubsetID to CustomizationID

 - Change all SubTotal to Subtotal

Individual files:

   UBL-CreditNote-2.0-Example.xml,
   UBL-Invoice-2.0-Example.xml:
	
      LegalTotal -> LegalMonetaryTotal

   UBL-Order-2.0-Example.xml:

      LegalTotal -> AnticipatedMonetaryTotal

   UBL-Quotation-2.0-Example.xml:

      LegalTotal -> QuotedMonetaryTotal

   UBL-DespatchAdvice-2.0-Example.xml,
   UBL-Invoice-2.0-Example.xml,
   UBL-ReceiptAdvice-2.0-Example.xml:

      Wrapped LotIdentification in ItemInstance

This last change needs confirmation.  Somewhere between PRD2 and
PRD3 we seem to have introduced an ItemInstance wrapper for
several elements, one of which is LotIdentification.  But I can't
find this in the issues list and I'm not sure that simply wrapping
LotIdentification in ItemInstance makes sense in terms of business
semantics.

Jon