add isInputWithBias and isHiddenWithBias for RNNCell (#1515)
add isInputWithBias and isHiddenWithBias for RNNCell (#1515)

* add isInputWithBias and isHiddenWithBias for RNNCell

* default affine = true in BatchNormParams in recurrent layer

* add serializableSpec for recurrent

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