Fixed long-form article issue w/ calculate_best_node

* Test case included: businessinsider3 / http://www.businessinsider.com/larry-page-the-untold-story-2014-4

See https://github.com/jiminoc/goose/blob/master/src/main/scala/com/gravity/goose/extractors/ContentExtractor.scala#L227

Author: jeffnappi

goose/extractors.py

@@ -267,7 +267,7 @@ def calculate_best_node(self, article):
                 if (nodes_number - i) <= bottom_negativescore_nodes:
                     booster = float(bottom_negativescore_nodes - (nodes_number - i))
                     boost_score = float(-pow(booster, float(2)))
-                    negscore = -abs(boost_score) + negative_scoring
+                    negscore = abs(boost_score) + negative_scoring
                     if negscore > 40:
                         boost_score = float(5)