Fixed two bugs:
(1) mistakenly using cost as the feature value for the edge, should just be 1 indicating that the edge exists
(2) stopped allocating a dim-sized hash table for data instance (was never supposed to do that)

Changes:
(1) inverted the value of cost so that free links are true
(2) made sure tests are re-runnable with no errors so I can understand the effects of changes
Now computing precision, recall, and F-score since the data is skewed.
With the way the features are currently designed, regularization is not needed for either model and the intercept adds overwhelming bias.
minor cleanup prior to combining predictions from both models
multiplying probabilities from cost and existence models together for each edge in the path gets us to leaderboard position 47
Added sliding window bloom filters in preparation for adding additional features to the model.