[#33368] Wrong sprintf prevents escaping single quotes in tabs language strings values

To test, add some single quotes for example by changing
COM_NEWSFEEDS_EDIT_NEWSFEED="Edit News Feed"
to
COM_NEWSFEEDS_EDIT_NEWSFEED="Edit News' Feed"
Then edit a newsfeed: the tabs will not display.
![screen shot 2014-02-28 at 09 14 47](https://f.cloud.github.com/assets/869724/2292116/93ca7632-a050-11e3-93e6-355311fbfa26.png)
Patch and test again.
Also, these sprintf are useless as we have no variable value in the strings concerned.
http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=33368&start=0