Use 2 places after decimal for fiat currencies, 6 for digital

#727 
This should not be defined inline.  I would extract this to a constant (or a configuration option) into currencies.js using something like:

```javascript
var CRYPTO_CURRENCIES = _(["BTC", "LTC", "STR"]);
```

Then you could structure the statement: `if(CRYPTO_CURRENCIES.contains(path.currency_human)) {`