set up for openQA deployment

This adds openQA server, worker and dispatcher roles, and
applies them to the appropriate hosts. A few secret vars are
required. See trac #4958 for discussion.

roles/openqa/worker/templates/var-lib-openqa-share.mount.j2

@@ -0,0 +1,11 @@
+[Unit]
+Description=openQA shared assets
+ConditionPathExists=/var/lib/openqa/share
+
+[Mount]
+What={{ openqa_hostname }}:/var/lib/openqa/share
+Where=/var/lib/openqa/share
+Type=nfs
+
+[Install]
+WantedBy = remote-fs.target