Remove use of @mkdir / file permissions

It was hard to debug a problem that exist when this yii component doesn't have permissions to create directories.
This was for the uses of @mkdir that hides an error that yii can capture and inform to the user.
In my case was permission denied to create directory.

Also, when creating files without setting permissions properly to that file, depending on webserver configuration, you can get an access denied for reading the file in the tmp directory.

The last thing, importing inside widget->init the component route avoids to declare imports of the component and widget. Doing the import in init of widget makes the widget resolve this only when widget is instanciated, and letting the lazyloading system of yii work better.

Thank you for this component. It's great!