Doing this required adding columns to the virt and physical blockstores
tables to mark the attributes that will be considered for mapping.
Unmarked entries just flow through to the client-side.

This commit also introduces filesystem support in the form of passing
through a mount point to the client-side.  It is left to the client to
decide what filesystem and fs options to use to setup the space, including
any logical volume aggregation required to support the request.

* Translate bandwidth spec "~" to 10Kbps, and complain if any other value
  is used on a lan with blockstores.

* Allow blockstores to be fixed to nodes.  Shunt through cases where the
  node a blockstore is fixed to isn't a blockstore pseudo-VM via a
  features / desires hack.  We do this to avoid having a more heavyweight
  blockstore pseudo-VM representation show up when users just want more
  local disk space setup on their nodes.

Also, blockstores VMs can't be the sync server...

This call returns info about the HW on the node (duh!) for the benefit
of the upcoming "nodetest". It returns whatever info about the CPU, memory,
disks and network interfaces is in the DB. The info comes from a variety of
places:
  node_attributes, node_type_attributes, blockstores, blockstore_attributes,
  blockstore_type_attributes, and interfaces
at last count.

We will need to add some new node_type_attributes for cpu/memory.
Even though some of the info exists already (e.g., "memory", "frequency"),
I chose to use uniformly prefixed attributes (hw_cpu_*, hw_mem_*) to
make my tmcd-life easier.

amount a physical has is stored in the node types table, and the
per-vm memory requirement is stored in the nodes table. ptopgen
adds up usage, and subtracts from the total for the ptop file.
The vtop number comes from a virt_node_attribute table, and we
pass this through to the client side. Note that this is less
important for openvz, more so for XEN.

In the NS file:

	tb-set-node-memory-size $node 1024

Number is in MBs. The mapper defaults this to 128 for openvz and 256
for xen. Maximum is hardwired to 256 and 512 respectively. Need to
think about a good way to configure this in.

libvtop.

just handy for ensuring that two runs of the mapper put the lan
node in the same place when trying to debug a problem.

use more then it's allotted amount. We do this for both ingress and
egress. To handle ingress, I had to add another veth pair and bridge
between the physical device, but in retrospect, I could have done this
with an IFB on the existing root context side of the existing pair.
I will probably redo this, but wanted to get this working code into
the repo before I destroy it.

Not sure why this change was needed, but it wasn't working anymore.
Maybe this is a perl 5.10 -> 5.12 thing; how I was doing an eval of a
require to load an libosload_X module was no longer working.  The new
way is better anyway, but even after looking through the perlXdelta
pages, I didn't see a reason for this.

Oh well.