Add Payment Methods by the app only

[aashutoshrathi]

In this, we have to consider that the payment methods block in the bill will come empty in the future.
So we manually have to Print things in it (only those methods which are non-zero). Refer to the examples below.

If a bill has Cash as 50, Cheque as 15, and rest all zero.
The payment Methods' box in the bill will be completely filled by us.

So, it will have

Cash: 50
Cheque: 15

completely printed by us.