Missing named arguments in formatting call

Discovered via LGTM https://lgtm.com/projects/g/edx/edx-platform/alerts/?mode=list&severity=error

lms/djangoapps/course_goals/models.py

@@ -35,8 +35,8 @@ class CourseGoal(models.Model):
     def __unicode__(self):
         return 'CourseGoal: {user} set goal to {goal} for course {course}'.format(
             user=self.user.username,
+            goal=self.goal_key,
             course=self.course_key,
-            goal_key=self.goal_key,
         )
 
     class Meta: