fix some bugs

1. if the `dataType` of ajax has been set before, the `$.get` will not work property. fixed by changing it to `$.ajax`.
2. if the content of css rules contain brackets, (e.g. `background:url(xxx.jpg)`, the `REGEX` match will fail.
3. if `child` is a checkbox and the checkbox is `checked`, the status of class is wrong. fixed by toggle the class once more.