Add API for querying the serial number

Thanks go to Massimo Callegari for the initial patch and the request to remind
us again. Thanks also go to Denis and Sergey for working on the windows serial
number parser.

Task-number: QTBUG-31981
Change-Id: I60d882280f481eb99d275e0a9c81da50292b1c61
Reviewed-by: Massimo Callegari <massimocallegari@yahoo.it>
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>