Arise Integration

Some points to complete before integration is finished:
1. [x] Obtain data version from the jobspec stored in the model file.
2. [ ] Figure out assigning correct values to "greater_is_true".
3. [ ] Right way to configure which Regressor is used. Mainly, is it going to be automatic (like file extension based) or manually specified with a flag. How to organize this flag, is the question.