sets default for days_until_due to 0

erpnext/accounts/doctype/subscriptions/subscriptions.json

@@ -239,6 +239,7 @@
    "bold": 0, 
    "collapsible": 0, 
    "columns": 0, 
+   "default": "0", 
    "description": "Number of days that the subscriber has to pay invoices generated by this subscription", 
    "fieldname": "days_until_due", 
    "fieldtype": "Int", 
@@ -624,7 +625,7 @@
  "issingle": 0, 
  "istable": 0, 
  "max_attachments": 0, 
- "modified": "2018-02-26 15:25:15.673438", 
+ "modified": "2018-02-26 16:13:09.759890", 
  "modified_by": "Administrator", 
  "module": "Accounts", 
  "name": "Subscriptions",