Navigation us links update

1. Changing `life` to `lifestyle` for all editions.
2. Changing `culture` to `arts` for US edition.

![screen shot 2014-10-27 at 11 49 24](https://cloud.githubusercontent.com/assets/2579465/4790322/de97981a-5dcf-11e4-965e-23febadcbbd4.png)