Change copyrights and license headers from Nokia to Digia

Change-Id: Id0b72b8c895b0eab04a740bf83859c9b646dd911
Reviewed-by: Janne Anttila <janne.anttila@digia.com>
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>