Add Docker Support

[maxbundscherer]

I have added support for Docker.

In case you need it :)

[luarvique]

Thanks! Are you sure you are adding this stuff tot the right directory though? I think it should be in

https://github.com/luarvique/openwebrx/tree/master

but that repository already has Docker support. Maybe check it to make sure you are not doing the same job twice?

[maxbundscherer]

@luarvique - oh - i did not see this repo. Thanks!