SPF 24 (v2.4.0)

The SPF 24 (v2.4.0) release includes the following features:

• Custom headers can now be sent with requests (#390)
  • Set headers globally using the request-headers config
  • Set headers per-request using the headers option
• Error events will now provide the full XHR object in addition
  to the message for more detail (#402)
  • Thanks @tchiotludo!

This release fixes the following bugs:

• Script and style tags with alternate mime types (e.g.
  <script type="application/json">) will no longer be silently
  removed during response processing (#400)
  • Thanks @tchiotludo!

This release includes the following optimizations:

• Releases now contain the updated docs at the tagged commit
  (#406)