Enhance preview update automatically when `addToStack` is called

[pedrolsj]

Hi, I'm tring to upload a file taken from the users camera on a cordova aplication, for that i using the addToStack and after im calling the upload method, this works, the problem is when i try to do this in a multiple file uploader with image preview.

The addToStack does not add the preview (like a simple upload would do), so, when i call the upload i fall in a error on the _uploadSingle function because the fm.getThumb(id) returns null;

Steps to reproduce the issue

1. Set a multiple file upload with uploadAsync and showPreview enabled
2. Manually add a file through the addToStack method (blob file)
3. Call the upload method

Environment

Browsers

• [X ] Google Chrome
• [ X] Web view

Operating System

• Windows
• Android (with cordova)

Libraries

• jQuery version: 2.2.0
• bootstrap-fileinput version: 5.0.8