Support for cuda-9.0
Trying to compile against cuda-9.0. No luck so far.

```
//Arraymancer/tests/tensor/nimcache/arraymancer_init_copy_cuda.cpp: In function ‘void cuda_clone(int, int, int, int, const int*, const int*, int, T*, const int*, const int*, int, const T*)’:
//Arraymancer/tests/tensor/nimcache/arraymancer_init_copy_cuda.cpp:555:7: error: ‘cuda_apply2’ was not declared in this scope
       cuda_apply2<<<blocksPerGrid, threadsPerBlock>>>(
       ^
//Arraymancer/tests/tensor/nimcache/arraymancer_init_copy_cuda.cpp:555:20: error: expected primary-expression before ‘<’ token
       cuda_apply2<<<blocksPerGrid, threadsPerBlock>>>(
                    ^
//Arraymancer/tests/tensor/nimcache/arraymancer_init_copy_cuda.cpp:555:53: error: expected primary-expression before ‘>’ token
       cuda_apply2<<<blocksPerGrid, threadsPerBlock>>>(
```