HA 0.90.0b stream: installation

I had to run this to get the stream: component to install on a pi3.

General dependencies

sudo apt-get install -y python-dev pkg-config

Library components

sudo apt-get install -y
libavformat-dev libavcodec-dev libavdevice-dev
libavutil-dev libswscale-dev libswresample-dev libavfilter-dev

https://docs.mikeboers.com/pyav/develop/installation.html

yup I have seen this as well and have submitted a PR to the official docs