Keep focus on presentations and etherpad

[bgrozev]

When a new participant joins, their video replaces whatever is shown in the "big video" field. This is somewhat annoying if you're watching/presenting a presentation or looking at the etherpad.

Presentations and etherpad should not be replaced when a new participant joins.

[fippo]

That should be done in callactive.jingle -- https://github.com/jitsi/jitmeet/blob/master/app.js#L352
I wonder if we have a way to detect the number of video tracks there as well, we are currently also displaying audio-only streams in the large video element which doesn't make much sense.

[bgrozev]

Can't reproduce anymore