版本：
文件：
- https://cdn.bootcdn.net/ajax/libs/select2-bootstrap-theme/0.1.0-beta.10/select2-bootstrap.css
- https://cdn.bootcdn.net/ajax/libs/select2-bootstrap-theme/0.1.0-beta.10/select2-bootstrap.min.css
A theme for Select2 v4 and Bootstrap 3.