add KLDivergence feature; refactor codes

Running Baseline...
Running Logistic Regression...

Precision means:  0.783718756224 0.959489137574
Recall    means:  0.733317782656 0.958918770582
F-scores  means:  0.745415653606 0.958994534418

Precision - Paired t-test: t=-240.696062942, p=7.6771040658e-139
Recall    - Paired t-test: t=-274.143573117, p=1.99122126702e-144
F-score   - Paired t-test: t=-269.365226217, p=1.13275160812e-143