References
https://github.com/nathanmarz/storm-contrib
http://eugenedvorkin.com/implementing-top-10-most-popular-articles-in-real-time-with-storm-and-mongodb/
https://github.com/edvorkin/TrendingTopic
http://www.michael-noll.com/blog/2013/01/18/implementing-real-time-trending-topics-in-storm/