Renamed vision.h files to vision_cpu.h and vision_cuda.h (#1051)

torchvision/csrc/ROIAlign.h

 #pragma once
 
-#include "cpu/vision.h"
+#include "cpu/vision_cpu.h"
 
 #ifdef WITH_CUDA
-#include "cuda/vision.h"
+#include "cuda/vision_cuda.h"
 #endif
 
 // Interface for Python

torchvision/csrc/ROIPool.h

 #pragma once
 
-#include "cpu/vision.h"
+#include "cpu/vision_cpu.h"
 
 #ifdef WITH_CUDA
-#include "cuda/vision.h"
+#include "cuda/vision_cuda.h"
 #endif
 
 std::tuple<at::Tensor, at::Tensor> ROIPool_forward(

torchvision/csrc/cpu/ROIAlign_cpu.cpp

 #include <ATen/TensorUtils.h>
-#include "cpu/vision.h"
+#include "cpu/vision_cpu.h"
 
 // implementation taken from Caffe2
 template <typename T>

torchvision/csrc/cpu/nms_cpu.cpp

-#include "cpu/vision.h"
+#include "cpu/vision_cpu.h"
 
 template <typename scalar_t>
 at::Tensor nms_cpu_kernel(

torchvision/csrc/nms.h

 #pragma once
-#include "cpu/vision.h"
+#include "cpu/vision_cpu.h"
 
 #ifdef WITH_CUDA
-#include "cuda/vision.h"
+#include "cuda/vision_cpu.h"
 #endif
 
 at::Tensor nms(