MDL-37390 course: Set startdate properly for approved course

Once a course is approved the startdate is not set properly
This patch sets current midnight date as startdate and leave
enddate to 0

course/lib.php

@@ -3015,6 +3015,7 @@ public function approve() {
         $data->lang               = $courseconfig->lang;
         $data->enablecompletion   = $courseconfig->enablecompletion;
         $data->numsections        = $courseconfig->numsections;
+        $data->startdate          = usergetmidnight(time());
 
         $course = create_course($data);
         $context = context_course::instance($course->id, MUST_EXIST);