implement 'contributions' exported proposal property

app/Console/Commands/UpdateSiteProposals.php

@@ -109,6 +109,7 @@ class UpdateSiteProposals extends Command
         $prop->{'donate-url'} = url("projects/{$proposal->subaddr_index}/donate");
         $prop->{'gitlab-url'} = $proposal->gitlab_url;
         $prop->{'local-url'} = '/proposals/'. pathinfo($proposal->filename, PATHINFO_FILENAME) . '.html';
+        $prop->contributions = $proposal->contributions;
         $prop->milestones = $proposal->milestones;
         $prop->{'milestones-completed'} = $proposal->milestones_completed;
         $milestones_percentage = min(100, (int)(($proposal->milestones_completed * 100) / $proposal->milestones));