Feature/metrics endpoint

/to @rmg for review

/to @chandadharap to try out, this may make your datadog stuff easier.
It means `scope: null` is provided as option to strong-agent-statsd below, see [docs](https://github.com/strongloop/strong-agent-statsd/blob/master/README.md#publisher--requirestrong-agent-statsdoptions): "options.scope (String) A scope to prepend to the metric name before publication, default is none."