Docker images for raspberry pi

Description

Currently the way to install gitlab on raspberry pi is through the packages in official repos which is far from ideal, because it's neither isolated nor guaranteed to work across every raspberry pi setup.

Proposal

I propose that GitLab has official raspberry pi docker images

Links / references

Raspberry pi has had Docker support for about half a year now https://www.raspberrypi.org/blog/docker-comes-to-raspberry-pi/