Fixed width of congrats message

Before, the congratulations message when done reviewing would sometimes be wrapped on the left side like this:

![before](https://cloud.githubusercontent.com/assets/5547518/2750465/215b8046-c87d-11e3-9119-0cc3904d5297.png "Before")

I changed the layout_width to be consistent with the other stuff that is displayed there.

![after](https://cloud.githubusercontent.com/assets/5547518/2750468/3afc5926-c87d-11e3-84c6-d001caf930c6.png "After")