* Fixed issue #3069 by adding in_channels
* Registerd group_conv2d_nchw as topi compute
* Improved by checking tag value
* Removed group_conv2d_nchw topi registration
* Added test for relay group_conv2d_nchw
* Added assertions to forbid small group size
* Removed hard-coded oc_block_factor
* Added explanatory comments to group_conv2d_nchw_cuda
* Updated group_conv2d_nchw_cuda schedule
Removed 'direct' CUDA tests
* Reverted an accidental change in a conv2d test
* Fixed indentation problems
* Fixed a mis-commented line
* Reverted change in group_conv2d_nchw tag
* Removed commented int8 group_conv2d test
* Fixed group size assertions in group_conv2d_nchw_cuda
