Add author_id to response from new:message in conversation channel

Author: joshsmith

lib/code_corps_web/channels/conversation_channel.ex

@@ -26,6 +26,7 @@ defmodule CodeCorpsWeb.ConversationChannel do
     channel = "conversation:#{conversation_part.conversation_id}"
     event = "new:conversation-part"
     payload = %{
+      author_id: conversation_part.author_id,
       id: conversation_part.id
     }