Broke rc.storage into two phases, local blockstores and remote blockstores.
Setup of the former will also pick a best candidate for an old-school
"extrafs" and put the info in /var/emulab/boot/extrafs. This will be a
single line with one of DISK=foo, PART=foo, or FS=foo depending on whether
it found an available full disk, disk partition, or mounted filesystem
that we can use for mkextrafs (in the first two cases) or where we can
mooch off of (the last). This is only used in os_mountextrafs() right now;
i.e., I have NOT changed the mkextrafs script. So explicit invocations
by the user could still screw things up.

I have tested this with local blockstores and a non-nfs experiment
on both Linux and FreeBSD to make sure the most common sharing of space
works. I have not made any new images and I have not yet tested to make
sure I did not break non-blockstore, non-nfs experiments (i.e., where
we really should run mkextrafs).

So maybe don't make any new images til I get back, or else be prepared
to clean up after me.

Also fix a couple of nits.

FreeNAS 9 has reached a new level of broken in its handling of network
configuration. Essentially each time a vlan interface is added, or
IP configuration is added, it wipes all existing vlan configurtion
and recreates it from its database.  Worse, when IP addresses/aliases
are removed, it completely shuts off all network interfaces and
re-configures them from scratch. ALL interfaces.  All of them.
Every last one. Even those that are not in scope for the current
modification operation.

So, we now do ALL network manipulation, including create/destroy
vlan operations, behind FreeNAS's back.  As a consequence, FreeNAS's
UI will often not show the actual network configuration - it will only
list those things that have been set up statically through its
interfaces (command line or UI).

import image, create a new version of the image but with a null parent
pointer to indicate a new image not based on the previous or any other
local image. I know I said I wanted to just delete the current image but
decided I really didn't like that idea.

all versions of an image when doing a delete, and since we never actually
delete, we have to move the ndz/sig files out of the way (unless we have
used the purge option, which is ignored for emulab-ops images anyway). To
facilitate moving the images out of the way, mkdir a new home for all of
the files, with the name $imagename:$imageid. We change the path in the DB
as we move off each version of the image.

supported, see protogeni/test/blockstore.rspec. Caveat; only raw-pc works,
there is a bug in the client side that prevents blockstores from working
inside of XEN VMs.

then just success/failure. For example, lets tell the user if the reason
for failure is lack of nodes.

of an image based on an entirely new image file; Currently used from
the image_import with update path.

Add AllVersions() method to return a list of all versions of an image.

includes a confirm page.

regularly, but we can come back and run it with the -b option later. This
allows all the other changes to get done.

spotted when his client would disconnect before Createsliver returned.

import.