Docker tags

[DANAJK]

I'm not clear on the Docker tags and versions. We have some instructions in the Wiki:
https://github.com/SyneRBI/SIRF-SuperBuild/blob/master/docker/README.md

but on Docker Hub, the only recent versions have tags 'core' and 'core-gpu'.

[KrisThielemans]

This is due to failures building/testing. Current road-block is #506 which is due to CIL. I hope that @paskino, @gfardell or @epapoutsellis can have a look at what extra bits we need to install. Once that's fixed, the files on dockerhub should get automatically updated. I'm therefore closing this issue.