Spawn Video Feeds as users join through WebRTC

[tlsharkey]

Create new Video Feeds as participants join the call.

[siueric0010]

I believe this has been implemented via the addStreamer function call whenever a new consumer transport is created. However, we do need functionality for when they close. That means, on a close transport, we need a function that would remove the streamer.

[tlsharkey]

@tlsharkey implement closing feature #37