Add serviceMonitor to expose metrics

[jmvizcainoio]

Hi

I create a PR that create a serviceMonitor and a service to expose metrics and allow scrape to prometheus.
Also i was change the apiVersion to stable, the v1beta1 are deprecated on k8s 1.17+

Thanks

[codecov]

Codecov Report

Merging #111 (06ae8c9) into master (9d39b53) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #111   +/-   ##
=======================================
  Coverage   75.58%   75.58%           
=======================================
  Files           7        7           
  Lines         471      471           
=======================================
  Hits          356      356           
  Misses        101      101           
  Partials       14       14           

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