v1.0.0-beta.21

• #278 - Add new "reply" middleware action (@ericyhwang)
  • The "reply" middleware is called just before the backend is about to send a non-error reply to a client.
  • It's the flip side of the existing "receive" middleware action.
  • The middleware function gets a context with these properties:
    • request
    • reply
    • action (always 'reply' for this middleware)
    • agent
    • backend