Removed green lightbox

Green color for lightbox is not a really good idea. It's look like this:
![green_lightbox](https://f.cloud.github.com/assets/1638158/153510/9e0fee8c-75fa-11e2-89fb-04cfd9b6fcf2.png)

I think it's better to use an other color. I use the blue color for the success message: 
![blue_lightbox](https://f.cloud.github.com/assets/1638158/153515/b263596e-75fa-11e2-9f7c-b72e782988b8.png)