Sam demo (for discussion)

[granawkins]

This branch is the culmination of:

1. Greg adding support for specific sensors
2. the sam-educational branch
3. Ezio's config file
4. Greg and Grant's work at SAM with the Vernier Sensors
   *) It's also the backend for simoc-web #156 (above)

We discussed redoing these commits with some optimizations. Why don't we use this initially for review/comments/discussion, and then someone can create a new branch/PR to redo the commits.

[granawkins]

Seems like there should be one function to:

• Scan usb ports on device
• If a sensor is found, try to match it with an existing sensor class (e.g. VernierO2) and config.cfg label. If not found, log the details.
• If a matching class and config are found, boot the sensor and begin broadcasting.

This could be run on a like a ~5s loop, in a shell script on Raspberry Pi and/or in the server loop on sioserver.

Right now sensors are added manually/individually, e.g. python3 mocksensor.py -v --port 8081 -- except in the case of multiple vernier sensors, in which case they use asyncio.gather, or MCPRunner which uses threading. I believe Ezio had a better idea in mind for running multiple sensors together.

I think this way things could just work out-of-the-box, either in Gretchen's situation or for SAM, and replace a lot of redundant/case-specific tmux scripts.