[Libguestfs] RHEL 6 guest support

[Matthew Booth]

The following patches add RHEL 6 guest support to virt-v2v. This was actually
quite a lot easier than I expected.

* [PATCH 1/4] Update virt-v2v.conf for RHEL 6 virtio support
* [PATCH 2/4] Check kudzu exists before attempting to disable it
* [PATCH 3/4] Use dracut rather than mkinitrd if it's available
* [PATCH 4/4] Properly convert RHEL 6 guest console