Add observer and geo metadata

Use the heartbeat.run_from option to set the geographic location fields relevant to a given heartbeat instance.

The run_from option is used to label the geographic location where the monitor is running. Note, you can also set the run_from option on an individual monitor to apply a unique setting to just that monitor.

The run_from option takes two top-level fields:

• id: A string used to uniquely identify the geographic location. It is indexed as the observer.name field.
• geo: A map conforming to ECS geo fields. It is indexed under observer.geo.

Example:

heartbeat.run_from:
  id: my-custom-geo
  geo:
	name: nyc-dc1-rack2
	location: 40.7128, -74.0060
	continent_name: North America
	country_iso_code: US
	region_name: New York
	region_iso_code: NY
	city_name: New York