add top page

app/serializers/top_list_serializer.rb

@@ -0,0 +1,19 @@
+class TopListSerializer < ApplicationSerializer
+
+  attributes :can_create_topic,
+             :yearly,
+             :monthly,
+             :weekly,
+             :daily
+
+  def can_create_topic
+    scope.can_create?(Topic)
+  end
+
+  TopTopic.periods.each do |period|
+    define_method(period) do
+      TopicListSerializer.new(object[period], scope: scope).as_json
+    end
+  end
+
+end