some new layer and existing layer refactor (#957)
some new layer and existing layer refactor (#957)

* nn refactor

* fix code style issue

* add python api

* change back the layers

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