Change copyrights and license headers from Nokia to Digia

Change-Id: I4060147644d7ca34ccff71b3deb30e242b611dab
Reviewed-by: Janne Anttila <janne.anttila@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>