The older (unsupported AirCam) models behave differently and also apparently
suffer some under the last release of the NVR that supported them. Since they
are EOL and not supported by current software, filter them out so we don't
break while trying to extract an image from them.
This adds tests for the uvc camera module. It's a good thing too,
because I found a few bugs which are fixed here as well:
- Graceful handling of non-integer port
- Failure to take the first host that works when probing host,internalHost
- Failure to detect if neither of them actually work
This also converts the code to only call add_devices once with a listcomp.