[TASK] rename debug mode button (RT-2796)

Debug mode button say 'turn on debug mode' rather than pretend

before
![rt-2796-before](https://cloud.githubusercontent.com/assets/2035357/5273378/faa712ca-7a8e-11e4-81fc-c9ae30657c35.jpg)

after
![rt-2796-after](https://cloud.githubusercontent.com/assets/2035357/5273380/ff156410-7a8e-11e4-8bb1-f252db2169f3.jpg)