add notification permission status

README.md

@@ -111,6 +111,7 @@ WiFi options:
 
 ```js
 BluememeUtils.requestPushPermission(success, error);
+BluememeUtils.getPushPermissionStatus(success, error);
 BluememeUtils.getFirebaseToken(function (result) {
   console.log(result.token);
 }, error);
@@ -134,6 +135,31 @@ BluememeUtils.getInitialNotification(success, error);
 BluememeUtils.stopNotificationListener(success, error);
 ```
 
+`getPushPermissionStatus` 只读取当前系统通知状态，不弹授权框。可用于填充后端 `NotificationsEnabled`。
+
+返回示例：
+
+```json
+{
+  "type": "notification",
+  "platform": "Android",
+  "enabled": true,
+  "granted": true,
+  "runtimePermissionGranted": true,
+  "appNotificationsEnabled": true,
+  "authorizationStatus": "authorized",
+  "missing": []
+}
+```
+
+推荐注册 token 前调用：
+
+```js
+BluememeUtils.getPushPermissionStatus(function (status) {
+  var notificationsEnabled = status.enabled === true;
+}, error);
+```
+
 事件也会派发到 `window`：
 
 - `bluememeutils.token`