Add support extra_cdrom_ks installation test for WinNT6.0 guest

In RHEL7.0,  floppy drive has removed from installation kernel and ramdisk,  install rhel7 guest from floppy test was block and  floopy does not support by qemu if machine type is 'q35' too, so we need to add support extra_cdrom_ks test for windows guest. This patch set do that we want to do.

Thanks,
Xu