added popular exploration, added order:rank

app/presenters/post_set_presenters/popular.rb

@@ -0,0 +1,34 @@
+module PostSetPresenters
+  class Popular < Base
+    attr_accessor :post_set, :tag_set_presenter
+    delegate :posts, :date, :to => :post_set
+    
+    def initialize(post_set)
+      @post_set = post_set
+    end
+
+    def prev_day
+      date - 1
+    end
+    
+    def next_day
+      date + 1
+    end
+    
+    def prev_week
+      date - 7
+    end
+    
+    def next_week
+      date + 7
+    end
+    
+    def prev_month
+      1.month.ago(date)
+    end
+    
+    def next_month
+      1.month.since(date)
+    end
+  end
+end