Format "formatted_amount_accepted"

"formatted_*" numbers are stored as formatted string. This was not the case for "formatted_amount_accepted", e.g.:

https://masterchain.info/tx/db8641b0e8bb6dc3694404668893a67163b5745095d51f83b72ba4cd6213f21c.json

"formatted_amount_accepted": 0.0018149999689180962,
"formatted_amount_bought": "0.0",
"formatted_amount_requested": "1.7",
"formatted_fee": "0.0001",
"formatted_price_per_coin": "0.07"

Which becomes:

"formatted_amount_accepted": "0.001815",

Balances and consensus checks were similar before and after applying this change.