[Fuego] Dockerfile vs install-debian.sh

Hi guys,

I was just looking into how to install Fuego without a Docker container 
(since the CHANGELOG says it's possible). Apparently, that's what 
install-debian.sh is good for (or is there something else, that I missed?).

But honestly, this script seems like a halfhearted attempt to me and 
strongly violates the DRY principle. It is clearly descendant from 
Dockerfile, but did not evolve with it. Several later modifications in 
Dockerfile did not make it to install-debian.sh. How do you plan to keep 
these files in sync?

I propose to only let install-debian.sh have all the code that sets up 
the OS and installs all requirements. The Dockerfile instead should do 
(almost) nothing but execute install-debian.sh.

An additional benefit of that method is that it will be much easier to 
also keep Dockerfile.nojenkins in sync with the standard Dockerfile. 
Because here we have the same problem of lots of copied code, that is 
slowly drifting apart. We might even not need Dockerfile.nojenkins 
anymore at all.

I can offer to implement this, unless there are strong objections by anyone.

Regards, Georg