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.