If we cannot resize the given file (files such as ICO can't be, for
SVG it makes no sense), then we should just return the original file
as is rather than an error.
Added the * option that is not affected by the 'varying-pagetype'
problem that has been detected and issued @ MDL-30564. So now, it's
(back) possible to define coursecat blocks to be spread over children
coursecats/courses/modules (contexts).
