additional user in slurm base docker image

roles/cobald/vars/cobald-slurm.yml

@@ -1,5 +1,5 @@
 cobald_image_tag: slurm
-cobald_docker_base_image: "{{slurm.base_image}}"
+cobald_docker_base_image: "slurm:slurmd"
 cobald_docker_default_command: False
 cobald_docker_network: "{{slurm.network}}"
 cobald_domainname: "{{slurm.domain}}"