Start the GPU Faust class python wrapper with the Faust constructor (from...

Start the GPU Faust class python wrapper with the Faust constructor (from numpy arrays), display function and multiply by a numpy aray.

Update to gpu_mod@35e44f6d.

============ Test case
from pyfaust import Faust
from numpy.random import rand
from numpy.linalg import norm

M = rand(10,10)
gpu_F = Faust([M], gpu=0)
print(gpu_F)
gpu_FM = gpu_F*M

cpu_F = Faust([M])
cpu_FM = cpu_F*M

print('error gpu/cpu:', norm(cpu_FM-gpu_FM)/norm(gpu_FM))
=========================