Add Audio/Video sharing to therapy session page

[pierd]

Depends on #8

[pierd]

WebRTC samples can be useful here: https://github.com/webrtc/samples

[pierd]

Another option: https://www.twilio.com/video/pricing

[pierd]

I did a bit more research and we would need a signalling channel (that will be the same for chat system) and we can’t get that for free (we need an extra instance to host redis)

[dav-armour]

https://unboxed.co/blog/actioncable-on-aws/
They seem to be using postgresql instead of redis. Don't understand most of that article so can't tell if that's viable.
https://www.cmgresearch.com/2017/05/11/step-7-action-cable-on-elastic-beanstalk.html
He uses ElastiCache to do the redis part which we can get free for 12 months.