Clear the cache and remove all the files from disk.

def clear(self):
        """
        Clear the cache and remove all the files from disk.
        """
        self.log(u"Clearing cache...")
        for file_handler, file_info in self.cache.values():
            self.log([u"  Removing file '%s'", file_info])
            gf.delete_file(file_handler, file_info)
        self._initialize_cache()
        self.log(u"Clearing cache... done")