add vars.yml

[ivotron]

• read monitor, osd and client roles for containers from files written at setup time

• read monitor IP address and CIDR from file too

• define variable with list of devices

• add conceptual to get bisection bandwidth

• add fio to get 4MB seq write bandwidth and 4k random read

• add radosbench item with equivalent options:

  image: your/ceph:image
  privileged: true
  pid: host
  network_mode: host
  environment:
    OSD_DEVICES: '{{ osd_devices }}'
  volumes:
  - '/dev:/dev'