Can create countdown timers

lib/helpers/posts_helper.dart

@@ -153,6 +153,11 @@ class PostsHelper {
                 type: MediaType.parse("application/pdf")));
         break;
 
+      case PostKind.COUNTDOWN:
+        request.addInt(
+            "time-end", (post.timeEnd.millisecondsSinceEpoch / 1000).floor());
+        break;
+
       default:
         throw Exception("Unsupported post type :" + post.kind.toString());
         break;