Add microphone filtering

[rbray89]

This change introduces pulseaudio as a go-between for audio processing so that we can use the echo-cancel module to "clean up" the microphone. This is especially useful when white-noise machines are running in the background.

[ivadim]

Hi @rbray89 This looks awesome. I tried myself to setup filtering before using containers but configuration became too complex...

Can I ask you to fix small issues before I merge this?

• You removed this line:

• ./configuration/nginx/.htpasswd:/etc/nginx/.htpasswd

  
  idea behind this as you can setup nginx password before running container... 

• Build is failing with error

  
  Step 4/5 : COPY audio_entry.sh /
  COPY failed: stat /var/lib/docker/tmp/docker-builder519891823/audio_entry.sh: no such file or directory

it happens because working directory is outside of the current Docker file's directory... 
https://github.com/ivadim/fruitnanny/blob/ca810c75326beb8cf0347b066b9f6116bc1b446b/azure-pipelines.pr.yml#L29
https://github.com/ivadim/fruitnanny/blob/ca810c75326beb8cf0347b066b9f6116bc1b446b/azure-pipelines.yml#L36

I think you can just add `cd` to  `docker/$(stage.name)`

[ivadim]

@rbray89 thank you for the contribution 🙇 . I'll fix the build later