Ignore the default value when calculating if notifications are enabled

This is to make the "Enable desktop notifications" checkbox accurately reflect the user's preference. The device-level setting is still respected. 

Signed-off-by: Travis Ralston <travpc@gmail.com>

src/settings/controllers/SettingController.js

@@ -31,9 +31,11 @@ export default class SettingController {
      * @param {String} roomId The room ID, may be null.
      * @param {*} calculatedValue The value that the handlers think the setting should be,
      * may be null.
+     * @param {string} calculatedAtLevel The level for which the calculated value was
+     * calculated at. May be null.
      * @return {*} The value that should be used, or null if no override is applicable.
      */
-    getValueOverride(level, roomId, calculatedValue) {
+    getValueOverride(level, roomId, calculatedValue, calculatedAtLevel) {
         return null; // no override
     }