optionally enable port 9090 on the prometheus container

[pcuzner]

9090 allows for adhoc graphing directly against prometheus. We should either support this by default, or have this feature defined in all.yml to allow the admin to open this port if required

[zmc]

We already publish the port on the container host: https://github.com/ceph/cephmetrics/blob/master/ansible/roles/ceph-prometheus/tasks/setup_container.yml#L15

Is this meant to be about the firewall?

[pcuzner]

yup