Use Config.fileTypes with mime-db backed MIME types; remove old archives.formats{}

core/mime_util.js

@@ -0,0 +1,10 @@
+/* jslint node: true */
+'use strict';
+
+const mimeTypes	= require('mime-types');
+
+exports.resolveMimeType		= resolveMimeType;
+
+function resolveMimeType(query) {
+	return mimeTypes.extension(query) || mimeTypes.lookup(query) || undefined;	//	lookup() returns false; we want undefined
+}