Merge branch 'dgx' into 'master'

Adding smux role to deploy tmux

See merge request hpc-team/ansible_cluster_in_a_box!250

roles/smux/README.md

+A role to setup smux
+
+use
+- { role: smux }

roles/smux/tasks/main.yml

+---
+- name: install tmux
+  yum: name=tmux state=present
+  sudo: true
+  when: ansible_os_family == "RedHat"