missing language string

COM_NEWSFEEDS_NUM_ITEMS changed to COM_NEWSFEEDS_NUM_ARTICLES as the language file uses ARTICLES not ITEMS

Before

![before](https://cloud.githubusercontent.com/assets/1296369/4642239/a6c3105e-5442-11e4-9073-e40551ebdbb2.png)


After

![after](https://cloud.githubusercontent.com/assets/1296369/4642256/d59665fc-5442-11e4-9d05-b65aef520ffc.png)