Allow video download resolution to be configurable.

[dialmaster]

Right now we have the video resolution hardcoded to try for 1080p in server\modules\downloadModule.js
We should make that a user configurable option, and expose it in the UI.
Something like "preferred resolution" with a dropdown including 4k, 1080p, 720p and 480p.

[harrylavell]

This would be great! Maybe even something like being able to pull the highest available resolution also.