add "disabled" class to read-only form buttons

media/js/devreg/init.js

@@ -15,7 +15,7 @@ $(document).ready(function() {
             .before(gettext('This feature is temporarily disabled while we ' +
                             'perform website maintenance. Please check back ' +
                             'a little later.'))
-            .find('button, input, select, textarea').attr('disabled', true);
+            .find('button, input, select, textarea').attr('disabled', true).addClass('disabled');
     }
 });
 

media/js/mkt/init.js

@@ -16,6 +16,6 @@ $(document).ready(function() {
             .before(gettext('This feature is temporarily disabled while we ' +
                             'perform website maintenance. Please check back ' +
                             'a little later.'))
-            .find('button, input, select, textarea').attr('disabled', true);
+            .find('button, input, select, textarea').attr('disabled', true).addClass('disabled');
     }
 });

media/js/zamboni/init.js

@@ -30,7 +30,7 @@ $(document).ready(function(){
     if (z.readonly) {
         $('form[method=post]')
             .before(gettext('This feature is temporarily disabled while we perform website maintenance. Please check back a little later.'))
-            .find('input, button, select').attr('disabled', true);
+            .find('input, button, select').attr('disabled', true).addClass('disabled');
     }
 });