fix tfnet cannot handle scalar (#795)
fix tfnet cannot handle scalar (#795)

* fix tfnet cannot handle scalar

* fix exmaple

* fix test

* fix test

* fix test

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