fixed button text when enabling/disabling extension via ajax (probably introduced in #1231)

lib/plugins/extension/script.js

@@ -72,7 +72,7 @@ jQuery(function(){
                     .removeAttr('disabled')
                     .removeClass('disable')
                     .removeClass('enable')
-                    .val(data.label)
+                    .text(data.label)
                     .addClass(data.reverse)
                 .parents('li')
                     .removeClass('disabled')