Add video plugin about zeo

[blizking]

We want to add video and audio support inside zeo.
Currently there are no ways to bring in media except for 3D models, which you could drag and drop in. We did have full media support in the old build but took it out to optimize it later i.e. now.

What we essentially need is a plane video player and mono audio output, out of a 'speaker'. Which we can configure later as 2.1, 5.1, 7.1, etc. channels. The plane video player has to be scalable and the ability to make it curved or 360 would be a plus. Currently support for mp4, mkv and avi should be sufficient and mp3 support for audio should be enough too.

This feature has to work both in the Vive and PC.

There are tonnes of resources available for adding 2D/360 video, Here's a link that you might find useful for audio.
http://smus.com/spatial-audio-web-vr/

[blizking]

A few other notes for the video playback, The video would be streamed across all users and websocket messages would be used to communicate play, pause and scrubbing between players.

We would also have to add a draw distance to stop video playback for each particular user as they navigate away from the screen. Instead of manually (re-)implementing draw distance and persistence across restarts, we can just make the speakers/screen be objects in the objects module. The objects module already handles loading/unloading based on range and saving data to the backend.

For the audio spatialiazation you can find support for it in our core API over here.
https://github.com/modulesio/zeo/blob/master/core/engines/somnifer/client.js