First steps on converting FeedSub into the pub/sub basis for OStatus communications:

* renamed FeedSub plugin to OStatus
* now setting avatar on subscriptions
* general fixes for subscription
* integrated PuSH hub to handle only user timelines on canonical ID url; sends updates directly
* set $config['feedsub']['nohub'] = true to test w/ foreign feeds that don't have hubs (won't actually receive updates though)
* a few bits of code documentation
* HMAC support for verified distributions (safest if sub setup is on HTTPS)

And a couple core changes:
* minimizing HTML output for exceptions in API requests to aid in debugging
* fix for rel=self link in apitimelineuser when id given

This does not not yet include any of the individual subscription management (Salmon notifications for sub/unsub, etc) nor a nice UI for user subscriptions.
Needs some further cleanup to treat posts as status updates instead of link references.

lib/httpclient.php

@@ -81,12 +81,13 @@ class HTTPResponse extends HTTP_Request2_Response
     }
 
     /**
-     * Check if the response is OK, generally a 200 status code.
+     * Check if the response is OK, generally a 200 or other 2xx status code.
      * @return bool
      */
     function isOk()
     {
-        return ($this->getStatus() == 200);
+        $status = $this->getStatus();
+        return ($status >= 200 && $status < 300);
     }
 }