Update torch api

[arokem]

Currently getting some deprecation warnings:

/Users/arokem/source/mri2mri/mri2mri/networks.py:23: UserWarning: nn.init.normal is now deprecated in favor of nn.init.normal_.
  init.normal(m.weight.data, 0.0, 0.02)
/Users/arokem/source/mri2mri/mri2mri/networks.py:27: UserWarning: nn.init.normal is now deprecated in favor of nn.init.normal_.
  init.normal(m.weight.data, 1.0, 0.02)
/Users/arokem/source/mri2mri/mri2mri/networks.py:28: UserWarning: nn.init.constant is now deprecated in favor of nn.init.constant_.
  init.constant(m.bias.data, 0.0)