Add occupancy sensors to dashboard

[gtfierro]

If a timeseries is tagged as an occupancy sensor

Metadata/Sensor = Occupancy
Metadata/Type = Sensor

then we should render it on the dashboard for the related zone as a little 👤 .

This is some nice feedback on the dashboard, but will require altering how occupancy sensors work. Right now, the KETI motes only give a little blip when they detect movement. This blip should extend out 5 or 10 minutes, and each subsequent blip should refresh that time. In other words, if a sensor detects occupancy, then it should continue to report occupancy for 5 minutes.

Not sure how other occupancy sensors behave, but we should standardize their behavior.