Shifu 0.2.6 Others

1. Add AUC Value in Eval Step

2. Add Distinct Count in Init Step (distinct count will be written in ColumnConfig.json)

3. Normalize missing value as mean value as a option

4. Add Shortcuts as 'norm', 'varsel'

5. Add CSV ColumnConfig File for ColumnConfig.json

6. Support HDP 2.6.0.2.2.4.2-2