Get rid of Left Hand Cards test

Stats show that, on wide screens (>1300px) in Feb 2014:

- ~540,000 clicks on in body links were recorded (linking to external and internal pages)
- ~5000 clicks on left hand cards were recorded (linking to internal pages)

These stats too little evidence for us to keep this feature.

![screen shot 2014-02-25 at 11 22 08](https://f.cloud.github.com/assets/85783/2256914/2506644c-9e0f-11e3-89f9-53a58efd4542.PNG)

![ ](http://s1.developerslife.ru/public/images/gifs/5b60fc91-d4c2-449d-a4ea-bb127bacd807.gif)