[#23] Removing the cross in {Use prepared questions} layout when retaking

Relative issue: #23
In a retake scenario, the cross appearing in ```Use prepared questions``` layout should not appear because at this moment, we are in the middle of a process. The teacher **already confirmed** previously he wanted to retake.
![screen shot 2014-04-11 at 18 33 03](https://cloud.githubusercontent.com/assets/3521208/2682176/15bcb954-c197-11e3-8a58-3ca57c880fdf.png)
![screen shot 2014-04-11 at 18 33 19](https://cloud.githubusercontent.com/assets/3521208/2682178/1928ab3e-c197-11e3-9764-fcd7400676f6.png)