* poke downloaded_since_sign on jamtrackright page

ruby/lib/jam_ruby/models/jam_track_right.rb

@@ -173,6 +173,10 @@ module JamRuby
     def update_download_count(count=1)
       self.download_count = self.download_count + count
       self.last_downloaded_at = Time.now
+
+      if self.signed
+        self.downloaded_since_sign = true
+      end
     end
 
     def self.list_keys(user, jamtracks)