Changed resolved label to closed

Changed "resolved" label in the open/resolved pie chart of the burndown page to "closed", as it makes more sense to show either all open/closed statuses, than just two hardcoded ones.
Differential Revision: https://phabricator.collabora.com/D976

rsrc/behavior-c3-pie.js

@@ -10,7 +10,7 @@ JX.behavior('c3-pie', function(config) {
         data: {
             columns: [
                 ['open', config.open],
-                ['resolved', config.resolved]
+                ['closed', config.resolved]
             ],
             type: 'pie'
         },