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.

plugins/OStatus/extlib/xml-feed-parser-bug-16416.patch

@@ -0,0 +1,14 @@
+diff --git a/htdocs/lib/pear/XML/Feed/Parser/RSS2.php b/htdocs/lib/pear/XML/Feed/Parser/RSS2.php
+index c5d79d1..308a4ab 100644
+--- a/htdocs/lib/pear/XML/Feed/Parser/RSS2.php
++++ b/htdocs/lib/pear/XML/Feed/Parser/RSS2.php
+@@ -321,7 +321,8 @@ class XML_Feed_Parser_RSS2 extends XML_Feed_Parser_Type
+      */
+     function getLink($offset, $attribute = 'href', $params = array())
+     {
+-        $links = $this->model->getElementsByTagName('link');
++        $xPath = new DOMXPath($this->model);
++        $links = $xPath->query('//link');
+ 
+         if ($links->length <= $offset) {
+             return false;