Fixes an issue where the device compute capability is larger than
the supported maximum of the CUDA runtime used to build ArrayFire.
This happens for example when you run the Turing card with a CUDA
runtime of 9.0. The compute capability of Turing is 7.5 and the
maximum supported by the runtime is 7.0/7.2. Before this change
we were only checking the major compute capability and not checking
the minor version to set the max compute capability of the device.
This caused errors like:
In file src/backend/cuda/compile_module.cpp:266
NVRTC Error(5): NVRTC_ERROR_INVALID_OPTION
Log:
nvrtc: error: invalid value for --gpu-architecture (-arch)
This commit also updates the error messages for failure cases.

The utility header in cuda_fp16.hpp is not included automatically
in CUDA 9. Additionally we need to pass the
--device-as-default-execution-space flag to nvrtc for JIT and
non-JIT kernels

* The moduleKey is an size_t object so the maximum number of digits
  it can have is 20 so the format length for that value is updated
* The runtime check messages are always logged (but not displayed)
  Errors are still only thrown in debug modes
* Display the compute capability of the CUDA device along with
  its name and other stats
  example:
  Found device: Quadro T2000 (sm_75) (3.82 GB | ~3164.06 GFLOPs | 16 SMs)