Add webrtc sanzu server

[serpilliere]

We will track webrtc work here
Discussed at #124

It seems that the yuv444 has been landed in the h264 webrtc decoder, at least for chrome:
https://bugs.chromium.org/p/chromium/issues/detail?id=1251096
status fixed at the beginning of the year.
This means that once we port the webrtc feature to the sanzu server, we may be able to encode the video stream using this format, so having an interesting image quality.

(I didn't test it yet)