Added Micrometer support

And through micrometer, you can now monitor AppOptics, Atlas, Datadog, Dynatrace, Elastic, Ganglia, Graphite, Humio, Influx, JMX, KairosDB, New Relic, Prometheus, SignalFx, StatsD, Wavefront.

Spring uses Micrometer as its monitoring tool.

https://micrometer.io/docs