Add support for `host` in agent config

[cgarvis]

Add support for `host` in agent config

[eksoverzero]

When you say 'host', what would you like to use this for?

You can specify the URL which can be changed from the default http://localhost:9200 to the suit your needs. Say your Elasticsearch host was example.com and running on port 9201 you would set this to http://example.com:9201

The reason the host is not being used as the name in New Relic is because one host can have one index or multiple indices you would like to monitor. So a simple name is used.

If you would like to monitor all indices on a host and have the host show in New Relic, your config file could look like this:

newrelic:
  #
  # Update with your New Relic account license key:
  #
  license_key: 'YOUR_LICENSE_KEY_HERE'
  #
  # Set to '1' for verbose output, remove for normal output.
  # All output goes to stdout/stderr.
  #
  verbose: 1

#
# Agent Configuration, describe your nginx instances here
#
agents:
  elasticsearch_stats_agent:
    -
      # Application name
      name: "example.com"
      # Index name
      # using "_all" with provide stats for all indices
      index: "_all"
      url: "http://example.com:9200"