Add Dockerfile.

[liske]

This PR contains a simple Dockerfile for PaWebControl.

[Siot]

Hi @liske !

I'm trying to check thePR but I have some docker doubts (I'm a docker beginner). I've created the docker image
docker build -t pawctl .

and then
docker run --net=host pawctl

But throws an exception because pactl its not available. How did you connect with host pactl?

Thank you