You are currently using the Jekyll Bootstrap framework which has a known incompatibility with Jekyll v3.1. To fix this incompatibility, change page.theme.name in _includes/JB/setup to layout.theme.name. Your site may not build properly until this change has been applied. For more information, see http://jekyllrb.com/docs/upgrading/2-to-3/#layout-metadata.
I believe this fixes #7