Fix notification value for android download Manager

README.md

     <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
 +   <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />                                               
 +   <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />                                              
-
++   <uses-permission android:name="android.permission.DOWNLOAD_WITHOUT_NOTIFICATION" />
     ...
 
 ```

android/src/main/java/com/RNFetchBlob/RNFetchBlobReq.java

             if (options.addAndroidDownloads.getBoolean("useDownloadManager")) {
                 Uri uri = Uri.parse(url);
                 DownloadManager.Request req = new DownloadManager.Request(uri);
-                req.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
+                if(options.addAndroidDownloads.getBoolean("notification")) {
+                    req.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
+                } else {
+                    req.setNotificationVisibility(DownloadManager.Request.VISIBILITY_HIDDEN);
+                }
                 if(options.addAndroidDownloads.hasKey("title")) {
                     req.setTitle(options.addAndroidDownloads.getString("title"));
                 }