版本：
文件：
- https://cdn.bootcdn.net/ajax/libs/PullToRefresh/0.1.1/ptr.css
- https://cdn.bootcdn.net/ajax/libs/PullToRefresh/0.1.1/ptr.js
- https://cdn.bootcdn.net/ajax/libs/PullToRefresh/0.1.1/ptr.min.css
- https://cdn.bootcdn.net/ajax/libs/PullToRefresh/0.1.1/ptr.min.js