Support ML Vector for NNFrames. (#989)
Support ML Vector for NNFrames. (#989)

* support ML vec

* deprecate Vector Preprocessing

intel-analytics/BigDL,yangw1234/BigDL,yangw1234/BigDL,yangw1234/BigDL,intel-analytics/BigDL,intel-analytics/BigDL,intel-analytics/BigDL,yangw1234/BigDL