praveen|customising payment screen
praveen | styling changes to the bill
praveen|cleaning up commented code
praveen|making change to remove round-off from the New Charges in the bill
praveen| rounding off to nearest 2.5
praveen|reporting formatting changes
Banka | 1) Adding discount heads in seed.
        2) Making product categories' name singular
        3) Deleting default service product.
praveen|removing round off from bill
Banka | 1) Adding seed data for RSBY payment method
        2) Adding seed data for unit of measure
praveen|overriding the default template
praveen|confirm payment of invoice if balance is 0
Banka | Making UoM & Batch No column readonly in sales order to reduce number of tabs
prvaeen|replacing internal ref in the bill
praveen| adding line after discount
Banka | Changed date_order in sale.order class to be a datetime.
        Changed filters in sale.order view to reflect this change
Banka | Adding filters for delivery orders
praveen| dont confirm payment if it is a refund
praveen|cleaning up code
praveen|Add discount head to the bill
praveen|adding round off to new charges