Code makes fisher information matrix be 0

[dvoina13]

There's a bug on line 81 of model.py Should be: self.F_accum[v] = torch.add(torch.Tensor((self.F_accum[v])), torch.pow(loglikelihood_grads[v], 2).data)

(as far as I could see for the latest versions of torch, torch.add needs an output). The way code is written self.F_accum never gets updated and the Fisher matrix is just 0.