minor fix no-copy

erpnext/stock/doctype/delivery_note/delivery_note.json

@@ -180,7 +180,7 @@
    "fieldtype": "Data", 
    "hidden": 0, 
    "label": "Customer's Purchase Order No", 
-   "no_copy": 1, 
+   "no_copy": 0, 
    "oldfieldname": "po_no", 
    "oldfieldtype": "Data", 
    "permlevel": 0, 
@@ -1013,7 +1013,7 @@
  "idx": 1, 
  "in_create": 0, 
  "is_submittable": 1, 
- "modified": "2014-12-16 10:37:08.934881", 
+ "modified": "2014-12-22 14:58:19.575566", 
  "modified_by": "Administrator", 
  "module": "Stock", 
  "name": "Delivery Note",