Make docker images from scratch

[loeiten]

This will reduce their size, and reduce the risk of them being deprecated.

• PBS image
• SLURM image

https://stackoverflow.com/questions/19104847/how-to-generate-a-dockerfile-from-an-image

[loeiten]

SLURM resources:
https://github.com/Artlands/Install-Slurm
https://github.com/giovtorres/docker-centos7-slurm/blob/master/Dockerfile
https://slurm.schedmd.com/quickstart_admin.html