unit tests for 3D and 2D tests update

[dkazanc]

Adding 3D unittests and 2D tests update with #207 consideration.

@paskino mentioned:

This may not be sufficient to run the GPU tests.

In CIL we also verify that a NVIDIA GPU is installed by calling nvidia-smi along these lines

#nvidia
try:
subprocess.check_output('nvidia-smi')
has_nvidia = True
except:
has_nvidia = False