Add cuda current device set/switch/get, counting devices capabilities...

Add cuda current device set/switch/get, counting devices capabilities (faust_cuda_device module), update tests and MatSparse/Dense<FPP,GPU2>.

Adding test_get_device and update test_move (matrix to another device) in test_matdense_gpu_mod.cpp.in test_matsparse_gpu_mod.cpp.in.
New function getDevice() in MatSparse<FPP,GPU2>, MatDense<FPP,GPU2>.