Send uptime info to New Relic

[mountaindude]

Uptime info can today be stored in InfluxDB and/or shown on screen.

While Grafana has really good looking visuals, New Relic does provide good monitoring features and is used by many corporations.
New Relic does offer a good way to monitor services like Butler (for both availability, uptime and other metrics) and other tools in the Butler family.

Make it possible to post uptime metrics to NewRelic:

• application/json encoded body
• API key configurable in config file or via command line option
• Configurable http headers (metadata that should be passed to the monitoring service, ...)
• Configurable static fields in the payload
  • key-value pairs defined in config file
• Configurable dynamic that can be individually enabled/disabled
  • Butler memory usage
  • Butler uptime