Sandy: add 3b,3z and 4a

The main changes including:
1. add step 3b, 3z and 4a
2. modify the directory for the files (from ‘data/1.csv’ to
‘../data/1.csv’)
3. change taku’s feature selection from 4a to 4b (according to
readme.text)
4. change the output file for 4a from train_pool to train_preprocessing
(so the input for 4b need be changed)