Docker multiarch

[simonmicro]

• This will temporary break the docker builds, until I reconfigure the build properties inside the docker repo
• This will not modify the current tags, just add new - until the configuration is corrected (also inside the docker repo)
• Tested on amd64 and arm32v6
• ANY further change of the Dockerfiles need to be done inside EVERY file for EVERY architecture from now on

This implements #92

[simonmicro]

I object - according to https://docs.docker.com/engine/reference/builder/#maintainer-deprecated the MAINTAINER command is deprecated (and at the moment it is not even shown inside the docker manifests anymore). If you wish to be listed as maintainer I / you could use the LABEL (I am very sorry, that I removed the command, but I thought it would be better to remove the deprecated stuff when I am at it...). I did not do that, because from my perspective the git history is enough...

[simonmicro]

@6ec123321 Okay, thanks! I again emphasize that, if you wish, you can add yourself back using LABEL. I did not intended to claim your work as mine. But yeah, we'll see what @SystemRage thinks about that 😀, I hope he will just accept the PR soon...

[SystemRage]

Only one thing before merging, if you can remove gimp files.
png images are enough.

[simonmicro]

@SystemRage Here you go!