Change copyrights and license headers from Nokia to Digia

Change-Id: Ieac8fb85896427cd5e3c6d91698c455a0dc9e495
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Janne Anttila <janne.anttila@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>