OStatus partial support for group subscriptions:

* detection of group feeds is currently a nasty hack based on presence of '/groups/' in URL -- should use some property on the feed?
* listing for the remote group is kinda cruddy; needs to be named more cleanly
* still need to establish per-author profiles (easier once we have the updated Atom code in)
* group delivery probably not right yet
* saving of group messages still triggering some weird behavior

Added support for since_id and max_id on group timeline feeds as a free extra. Enjoy!

plugins/OStatus/OStatusPlugin.php

@@ -107,11 +107,11 @@ class OStatusPlugin extends Plugin
 
     /**
      * Set up a PuSH hub link to our internal link for canonical timeline
-     * Atom feeds for users.
+     * Atom feeds for users and groups.
      */
     function onStartApiAtom(Action $action)
     {
-        if ($action instanceof ApiTimelineUserAction) {
+        if ($action instanceof ApiTimelineUserAction || $action instanceof ApiTimelineGroupAction) {
             $id = $action->arg('id');
             if (strval(intval($id)) === strval($id)) {
                 // Canonical form of id in URL?