Deformable_Convolution_V2

Tensorflow implementation of deformable convolution v2

This code is mainly base on https://github.com/kastnerkyle/deform-conv/tree/master/deform_conv

Made some modification according to Deformable_convolution v2 and support for input_feature which H and W are not equal.

Add a c++ implemention of gpu code in https://github.com/smallsunsun1/custom_ops, you can use the new code there.