Change copyrights and license headers from Nokia to Digia

Change-Id: If89e41b25a242ff376eacdf8790957bcf499cc66
Reviewed-by: Janne Anttila <janne.anttila@digia.com>
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>