Form/File will automatically delete empty storage locations, but assets

expect them to stick around.  Add a flag to Form/File.pm to prevent it
from deleting them.  Make sensitive assets use that flag.

lib/WebGUI/Asset/Wobject/Article.pm

@@ -125,6 +125,7 @@ sub definition {
 				fieldType=>"image",
 				deleteFileUrl=>$session->url->page("func=deleteFile;filename="),
 				maxAttachments=>2,
+                persist => 1,
 				defaultValue=>undef,
 				label=>$i18n->get("attachments"),
 				hoverHelp=>$i18n->get("attachments help")