Metrics reporter config

Example config:
~~~~
metricsreporter {
  enabled = true
  configFile = "conf/metrics-reporter-config.yaml"
}
~~~~

~~~~
$ cat conf/metrics-reporter-config.yaml
ganglia:
  -
    period: 30
    timeunit: 'SECONDS'
    groupPrefix: 'collins'
    gmondConf: '/etc/ganglia/gmond.conf'
~~~~