Add debugging logs.

lib/pleroma/web/websub/websub.ex

@@ -44,6 +44,7 @@ def publish(topic, user, activity) do
       |> to_string
 
       signature = sign(sub.secret, response)
+      Logger.debug("Pushing to #{sub.callback}")
       HTTPoison.post(sub.callback, response, [
             {"Content-Type", "application/atom+xml"},
             {"X-Hub-Signature", "sha1=#{signature}"}