MDL-35073 badges: Open badges integration

The badges feature allows to integrate Mozilla "Open Badges" to issue, assign,
manage and display digital badges in Moodle. This feature supports:
-- badge creation and issuing based on criteria
-- badge baking and verification service
-- direct pushing of internal badges to external backpack
-- interanl and external badge display in Moodle
-- Moodle block to display latest badges

lib/completionlib.php

@@ -1036,6 +1036,8 @@ class completion_info {
         }
         $transaction->allow_commit();
 
+        events_trigger('activity_completion_changed', $data);
+
         if ($data->userid == $USER->id) {
             $SESSION->completioncache[$cm->course][$cm->id] = $data;
             // reset modinfo for user (no need to call rebuild_course_cache())