use jquery for error msg in course_about

lms/templates/portal/course_about.html

@@ -20,7 +20,7 @@
           if(json.success) {
             location.href="${reverse('dashboard')}";
           }else{
-            document.getElementById('register_message').innerHTML = "<p><font color='red'>" + json.error + "</font></p>";
+	    $('#register_message).html("<p><font color='red'>" + json.error + "</font></p>")
           }
         });
       })(this)