Provide examples in standalone files

It would be good if the examples from https://johnny.github.io/jquery-sortable/ are also provided in standalone HTML files.

Since all CSS and JS code from the examples are stored only in two files (`application.css` and `application.js`), sometimes can be difficult to find out which segment of code correspond to each example (I have tried to copy the code show by the **Show me the code** buttons, but sometimes they do not fully work).

Providing these files would be helpful when learning how to use the library and when trying to use the examples in another page.