I think I'd prefer to see it hard-coded into a template so we can:

* delete the comments
* use our own `app_name`
* make sure to escape the Yaml so we don't have the same issue we just had with secrets.yml
* sort the keys
* use single quotes

```yaml
common: &default_settings
  app_name: '<%= app_name %>'
  audit_log:
    enabled: false
  browser_monitoring:
    auto_instrument: true
  capture_params: false
  developer_mode: false
  error_collector:
    capture_source: true
    enabled: true
    ignore_errors: 'ActionController::RoutingError,Sinatra::NotFound'
  license_key: '<%%= ENV['NEW_RELIC_LICENSE_KEY'] %>'
  log_level: info
  monitor_mode: true
  transaction_tracer:
    enabled: true
    record_sql: obfuscated
    stack_trace_threshold: 0.500
    transaction_threshold: apdex_f
development:
  <<: *default_settings
  developer_mode: true
  monitor_mode: false
production:
  <<: *default_settings
  monitor_mode: true
staging:
  <<: *default_settings
  app_name: '<%= app_name %> (Staging)'
  monitor_mode: true
test:
  <<: *default_settings
  monitor_mode: false
```