Support "don't always stream" option

[peterbarker]

Currently the next version of APSync will start a UDP video stream to a GCS. However, you have to fire up a web browser and visit port 8000 and select "start streaming". This is clunky and not particularly user-friendly for an out-of-the-box experience.

Proposal:

• Change that so that we always stream to whoever is getting the port 14550 telemetry stream.
• Add a checkbox in the port-8000 interface which can be unchecked to stop that automatic streaming.