[et-mgmt-tools] Cobbler/Koan get QEMU/KVM support

[Michael DeHaan]

I've committed some changes to koan to allow for provisioning of 
kemu/qemu guests.

To try this out:

yum install kvm qemu
(Guests will use hardware support if you have it, if not, they'll be 
emulated)

koan --server=bootserver.example.org --profile=foo --virt --virttype="qemu"

You do not need to do any thing special in cobbler -- your existing 
0.5.0 profiles/trees will work without modification.   In my testing, I 
installed
a Centos 5 guest inside of F7 -- and as long as you have sufficient RAM, 
it seems to work well.

This commit includes the new --virtpath parameter, which is useful if 
you would like to specify a location for the images to go.  Right now 
the default -- which is /really/ temporary, is "/opt/qemu".   I can do 
better.  I also need to test out the partitioning and volume group
management bits with Xen (this parameter supports things like 
--virt-path=partition:/dev/sdb1).

The qemu code pays attention to cobbler attributes such as memory size, 
kernel parameters, and disk size. 

The new parameters such as --virtpath and --virttype will be able to be 
set in cobbler, though I intend to keep the overrides available in koan 
for at least those parameters.    --virttype will default to "xen" as 
shipped because that's what we support officially in RHEL, though I 
think I'll let the cobbler system default be changeable in 
/var/lib/cobbler/settings so you don't have to specify it with each 
profile created.

I still need to customize the qemu support a bit more, clean up the 
code, and improve the options some, but I just wanted to pass along that 
it's there now for those that want to play with it.

--Michael