update vimeo regex to work with private videos

Fix taken from fancyapps#2498 and credit also to fancyapps#2532 for reporting this issue. 

Credit to @nate-thomas for the fix fancyapps#2498 (comment)

src/js/media.js

@@ -28,7 +28,7 @@
     },
 
     vimeo: {
-      matcher: /^.+vimeo.com\/(.*\/)?([\d]+)(.*)?/,
+      matcher: /^.+vimeo.com\/(\/)?([\d]+)(.*)?/,
       params: {
         autoplay: 1,
         hd: 1,
@@ -287,4 +287,4 @@
       }
     }
   });
-})(jQuery);
+})(jQuery);