Create /root/.tmux.conf if it does not exist

Currently, we use lineinfile against /root/.tmux.conf, however if the
file does not first exist the deploy-osa.yml playbook will fail.  This
commit simply updates the `Config Tmux` task by adding the create option
to lineinfile so that the config will get created if it doesn't first
exist.

Change-Id: I366c4a875c6e7c2482f28a46bb29a2882b773f30

multi-node-aio/playbooks/deploy-osa.yml

@@ -117,6 +117,7 @@
         owner: root
         group: root
         mode: 0644
+        create: yes
 
     - name: Run OSA
       command: "{{ item }}"