Maintain Release 1.3.1

Recommended Update !

This is an incomplete list among the many features added.

• Update
  • deconv2d_bilinear_initalizer for SegNet by @JoelKronander
  • fix BiDynamicRNNLayer to avoid error in gradient updating by @akaitsuki-ii
  • update cost function for TF12 by @zsdonghao
  • update BatchNormLayer for TF12 by @zsdonghao

This version works well under TF 0.10 and 0.11 backend, it also works well with TF 0.12 in most of the case, feel free to report if you found a bug. Many thanks!