Small utility function to get vector by index.
(cherry picked from commit 7d003e0)
Add Scala API for deeplearning.

- simple deeplearning call
- add an example of call usage
(cherry picked from commit 8ee8ee6)
Unified DRF API with deep learning API.

- Scala DRF API now supports the same style of
passing arguments via anynymous function filling
algorithm object
(cherry picked from commit dbf8d41)
Minor helper function for scala.
(cherry picked from commit 9a87973)
More API improvements.
(cherry picked from commit 0eb62fe)