Converting HVM to ParaVM

[broder]

If pygrub does what I think it does (i.e. if it can read the partition table), then it should be possible to change an HVM into a ParaVM.

If ParaVMs really get all of performance benefits we think they do, we should offer a clean path for people to turn their Alpha-grade HVMs into Beta-grade ParaVMs. All that should be necessary is that the user installs the right kernel, shuts down, frobs the database somehow, and turns the machine back on.

I would personally really like to see this feature, as I'd like to convert some of my VMs into ParaVMs instead of HVMs