Add the ability to specify the PHP script timeout

Thanks https://github.com/grantnorwood
See #4
Add uninstall.php file to remove option when plugin is removed

Thanks https://github.com/grantnorwood
Clean whitespace in HTML attributes

Thanks https://github.com/grantnorwood
Add "Move category by tag" feature

This features enables users to move posts belonging to a
specific tag to a new category.

Fix #4