Change license header to reflect that code is contributed

KDAB license headers in KD Tools copy replaced with Qt license headers.

Change-Id: I9f7f9ab0ec1a58322673f87074f2959445f6e938
Reviewed-by: Niels Weber <niels.weber@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>