Updated the path to the css files as they have now moved into a "css/" directory

within the lightbox2 module directory.  The layout of the admin screen has been
altered and javascript is loaded to enable / disable form elements depending on
what is checked.  The "lightbox2_plus" system variable has been renamed to
"lightbox2_lite" and the code updated accordingly.  The term "lightbox2 plus"
has been removed from all user visible elements on the admin screen.