CUDA version of ZhuRamananHOG

For the moment only the nested loops dealing with inputImage pixels has been treated.
It might be the most significant part of the improvments of this feature.

Improvments can still be made in the kernel:
* Using local or shared memory instead of global memory can improve the performances of the kernel
* Smaller kernels are better
* Too many data allocated by kernel?
* More efficient way of dealing with atomic adds - another split for instance