Hide Took N seconds if code editor is hided

Hide `Took 0 seconds` if the user want to see only the result

![screen shot 2014-11-04 at 6 09 57 pm](https://cloud.githubusercontent.com/assets/3139557/4897052/6959be78-6402-11e4-97e5-7f68fe1429b9.png)

![screen shot 2014-11-04 at 6 10 06 pm](https://cloud.githubusercontent.com/assets/3139557/4897053/6b9b2686-6402-11e4-8d7d-f28fdec121a1.png)