Improve holoport detection heuristics

[mattgeddes]

Currently, we have a pretty crude set of heuristics for detecting holoport and holoport plus models. It works for now, but once things take off and people start wanting to run HolOS on other hardware platforms, we're going to run into trouble. This issue tracks a few small improvements for being able to be more specific around how we assume a machine is a holoport. There are other issues for making it possible to override defaults to install on arbitary-ish hardware, so that work is not covered here.