Geo: Add a Prometheus exporter for Geo Log Cursor

Right now we can't use Prometheus metrics inside the Geo Log Cursor because there's no Web server exporter for this. We'd need to:

  1. Do what the sidekiq_exporter does and run a Web server
  2. Add Omnibus support to specify the prometheus_multiproc_dir dir for geo-logcursor
Edited by Stan Hu