Add keras highway (#1913)
Add keras highway (#1913)

* Add highway

* Fix unit test

* Add python support

* fix ut

* add module seri

* fix ut

* Add API doc

* Add Regularizer

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