JoomlArt has a bug in their CDN extension that incorrectly converts the inclusion of the Facebook Javascript library (loaded from Facebook) to be loaded from your CDN. Since it doesn't exist on your CDN, it doesn't work.
So, the line of code that looks like:
js.src = "//connect.facebook.net/en_GB/all.js";
Gets updated to look (something) like:
js.src = "http://cdn.mrig.in/connect.facebook.net/en_GB/all.js";
You'll need to contact JoomlArt for a fix and let them know that their CDN is incorrectly converting 'schemeless' CDN links.
Hope that helps. There's not a fix we can recommend in JFBConnect.
Alex