Fix product view carousel rendering

I've fixed product page carousel thumbnails rendering.

Before:

![capture decran 2014-01-24 a 11 50 22](https://f.cloud.github.com/assets/103900/1994034/63f4cbb4-84e5-11e3-9ccc-51fbba2eff02.png)

After:

![capture decran 2014-01-24 a 11 49 07](https://f.cloud.github.com/assets/103900/1994036/682374f6-84e5-11e3-8dab-f8c0d4da5726.png)