Improved `NSNumber` `formattedStringWithCurrency:` by setting the currency code only when necessary. Plus we only need to set the maximum fraction digits once
Fix for `NSDateFormatter` category, for cases where the dateFormat changed. Also a best practice is to set the locale to en_US_POSIX
`fromJson` now uses type checking. It can convert from string to number and vice-versa, if those 2 are mixed. If it determines any other inconsistency, it will not set that property and broadcast `APFromJsonTypesNotMatchingNotification`