IMPORTANT - fixed HubSub to properly fetch primary keys

In commit e95f77d34c HubSub lost the
'staticGet' function in a consolidation into the Managed_DataObject class.
This was done carelessly by me as HubSub::staticGet was actually taking
two arguments, none of which was a key and merging them in HubSub::hashkey()
(staticGet was renamed getKV 2a4dc77a63).

NOTE: This complements commit 7e4718a4eb which
fixed a similar issue for the Magicsig class.

plugins/OStatus/lib/hubprepqueuehandler.php

@@ -65,7 +65,7 @@ class HubPrepQueueHandler extends QueueHandler
             while (count($pushCallbacks) && $n < self::ROLLING_BATCH) {
                 $n++;
                 $callback = array_shift($pushCallbacks);
-                $sub = HubSub::getKV($topic, $callback);
+                $sub = HubSub::getByHashkey($topic, $callback);
                 if (!$sub) {
                     common_log(LOG_ERR, "Skipping PuSH delivery for deleted(?) consumer $callback on $topic");
                     continue;