Node.js agent v1.21.1

Notes

• Moved concat-stream from dev dependencies to production dependencies.

  Last week we released v1.21.0 but forgot to move a dependency. We've removed v1.21.0 from npmjs.org and this release contains the changes from that version.

• Support for display host names (originally in 1.21.0).

  The agent now has configuration settings to allow configuration of custom host names. Set process_host.display_name to enable this.

  If this config is not set, the agent will continue to use the host name found through an os.hostname() call. Should this lookup fail somehow, process_host.ipv_preference can now be set to 4 or 6 to configure the type of ip address displayed in place of the host name.