add CrossProduct Layer (#2273)
add CrossProduct Layer (#2273)

* add CrossProduct Module

* update scaladoc & unit tests

* make some modifications

* add python support

* fix bug in python wrapper

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