setAttribute fix

Author: adamschwartz

js/install.js

@@ -2,7 +2,7 @@
   var options = INSTALL_OPTIONS;
 
   Array.prototype.forEach.call(document.querySelectorAll('table'), function(table){
-    table.setAttribute('data-sortable');
+    table.setAttribute('data-sortable', '');
     table.add('sortable-theme-' + options.theme);
   });
 })();