Support for Prometheus and Grafana

[pdurbin]

dataverse-ansible supports Prometheus now that IQSS/dataverse-ansible#96 has been merged.

@pmauduit are following up with this by adding collectd and Grafana on top and are leaving comments here on the configs we are using and the commands we are running: IQSS/dataverse-ansible#99

As of this writing the following metrics are being tracked:

• CPU load
• Memory
• Glassfish heap usage

Here's a screenshot of how it looks.

With dataverse-ansible we are continuing to install everything on a single CentOS 7 box but here in Kubernetes land perhaps it makes sense to run the monitoring service in a separate pod/container.

[pdurbin]

@poikilotherm do you think we should use collectd or not? I noticed you called it a "shotgun" at http://irclog.iq.harvard.edu/dataverse/2019-08-29#i_103773 😄

[poikilotherm]

Relates to #59

[poikilotherm]

I added the basic support for the JMX exporter to the image, to be released with 4.18 images.
This does not close this ticket, as we should outline at least minimum deploys of Prometheus and Grafana in the guide. That might be just some other articles on the net (plenty out there), but give people a place to run to.