Improve the score of comments

The ranking of comments uses upvotes−downvotes. Thanks to David Ruescas (nVotes), I found a blog post from 2009 remarking that this is a wrong strategy (http://www.evanmiller.org/how-not-to-sort-by-average-rating.html). For instance, a comment with 100 upvotes and 0 downvotes and a comment with 1000 upvotes and 900 downvotes would be equally scored. One could expect this would be solved using the average rating (upvotes/(upvotes+downvotes)), however, such strategy is also inappropriate because there will be many comments with few votes and, therefore, high uncertainty. To solve the above problem, the blog post suggests using the lower bound of the Wilson score confidence interval. Please find the formula implemented in Ruby in the blog post, as well as this detailed explanation of why Reddit is using this method https://medium.com/hacking-and-gonzo/how-reddit-ranking-algorithms-work-ef111e33d0d9