Handle Unified Formats

IMO, it would be clearer if there were one function called `parseNumber` that did that and returned `null` if the number couldn't be parsed. You could use this function everywhere. In places where you want a `0` instead of `null`, you could use the `?` operator:

```coffeescript
mortgage:
  new_property_value: parse.number(lead.ProductInformation.PropertyInformation?.PropertyValue)
  first_mortgage_balance: parse.number(lead.LoanInformation.FirstMortgageBalance) ? 0
  second_mortgage_balance: parse.number(lead.LoanInformation.SecondMortgageBalance) ? 0
```