Show btc amount in readable format

[anktd]

Requested Here

Currently Expected Amount & Paid Amount is shown in exponential format in frontend here, need to make it human readable.

Possible options:

1. Show amount in decimal i.e. instead of 4.676e-5 ➡ 0.00004676 BTC
2. Show amount in satoshi i.e. instead of 4.676e-5 ➡ 4676 satoshi
3. Show amount in mBTC i.e. instead of 4.676e-5 ➡ 0.04676 mBTC

We can also consider displaying in multiple ways.