new interface: skus used in the system, aggregated by build, rack etc

[karenetheridge]

It might be useful to be able to visualize in the GUI where all the various types of hardware are in the system -- i.e. the number of devices using each sku, aggregated by build, rack etc.

The UI should be sketched out first and then the api endpoint(s) can be written to match.

e.g. something like GET /build/hardware_product or GET .../rack/hardware_product which would return a similar data structure to GET /build or GET .../rack along with a new object for each top level entity:

{
  "sku": {
    "sku123": 1,
    "sku456": 20,
   ... more skus => counts
  }
}