Wrong sprintf causes to not escape 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)
Also, these sprintf are useless as we have no variable value in the strings concerned.