Fix notification (details in description)

- Fix the dot being displayed when the user has 0 notifications.
- Added a message when there is no unread notification to be displayed.

core/static/core/navbar.scss

@@ -304,6 +304,11 @@
                   font-size: .8em;
                 }
               }
+
+              &.empty-notification {
+                text-align: center;
+                font-style: italic;
+              }
             }
           }