Better javascript administration for sitewide-/user-tags

The javascript version of sitewide-/user-tags administration still needs to be improved.
A 'true' ajax-based solution should include the following updates:

• add tags without the need to reload the page
• rebuild table if tags are removed (to retain odd/even pattern)
• make the table sortable
• incorporate multi-lingual tags administration (without the need for 'external' language switcher)

To achieve this we will need to implement ajax form submit features, which still degrade gracefully. Especially the complex form/table layout should be removed with the next major update. Some parts even dont validate cleanly.