fix issue with lineSpacing, no space was added between the lines. The co...

This is a very small fix for an annoying problem.
I'm using the following line to add lineSpacing:
`this.questionText.lineSpacing = 20;`

Then this happens:
![screen shot 2014-11-25 at 16 48 03](https://cloud.githubusercontent.com/assets/951290/5185899/f9967500-74c2-11e4-812f-ddd1f3dc228b.png)
Here the complete text moves 20px down.

This is what should happen (with the fix):
![screen shot 2014-11-25 at 16 48 40](https://cloud.githubusercontent.com/assets/951290/5185900/fc506a08-74c2-11e4-9675-e18eb449e405.png)
Here all lines have the correct lineSpacing of 20px.

Example: http://jsfiddle.net/q4r45cxq/