add sensors command with get and list subcommands

[majesticio]

Once available we could use the sensors resource similarly to locations. Perhaps we would only use get with thesensors_id, where the sensors_id would be discovered using the locations resource, and as such sensors command would not have any spatial queries available?

[russbiggs]

@majesticio let's open a separate issue related to this also figure out how to deal with /v3/locations/[locations_id]/sensors. Not sure if that would fall under the same interface described here (via a flag?) or what.