Supprt Date Format other than ISO 8601 in SQL++

The assumption that everyone uses the hard coded ISO 8601 format of "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'" for date representations is not a good one. For instance GO uses RFC 3339 which is a profile of ISO 8601. Our team of engineers have had issues with date queries because of differences in format. It would be nice to specify your own NSDateFormatter for the conversion of NSDate to JSON and back.