[Enhancement] Add Prometheus support (#556)

* Added prometheus to deps list

* WIP - screwing around with Prometheus and grafana

* Added basic prometheus config

* Updated docs in prom_ex module

* Updated README

config/config.exs

@@ -99,6 +99,12 @@ config :logger, :default_formatter,
 # Use Jason for JSON parsing in Phoenix
 config :phoenix, :json_library, Jason
 
+config :pinchflat, Pinchflat.PromEx,
+  disabled: true,
+  manual_metrics_start_delay: :no_delay,
+  drop_metrics_groups: [],
+  metrics_server: :disabled
+
 # Import environment specific config. This must remain at the bottom
 # of this file so it overrides the configuration defined above.
 import_config "#{config_env()}.exs"