I think Bootstrap. Its an opensource and well documented. And after if you can customize some options that will be great . And after all bootstrap uses are increasing day by day so people are meant to familiar with this working set. And Also you can get about 16000+ project about Bootstrap in github.
So i think it will be good. But actuality it bonded how the structure build in base. I mean css+js with ajax. So it will be best to discuss with User Interface Developer of Blurt-it
Bootstrap is a very nice framework because it allows you to implement some nice looking CSS and cool functions very quickly and effectively.
Foundation is not as comprehensive, and is less used, so if you want to become a professional front end developer I would recommend getting well acquainted with Bootstrap as it is the style that most clients will request or be impressed by.