vnode creation time linear with the number of images (currently there is
only one, although this support allows for different images for vnodes on
the same vhost).  LVM is currently the default, but I left the old code
too.  Right now, the master logical device for each image gets 8GB; the
snapshots each get 1GB for CoW data.  This all needs to be exposed to user
control somehow.

Also made a ton of resources unlimited, not that it has seemed to improve
performance though.

mkextrafs.pl now supports some basic LVM creation stuff.