Add bindings for .cpu() & .cuda() to script (#15904)
Summary:
Adding bindings for .cpu() and .cuda() to script.
It's worth noting that if the device remains unchanged, than the returned tensor aliases the input, but if it does change than they do not alias each other.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15904
Differential Revision: D13632879
Pulled By: eellison
fbshipit-source-id: 024a04f267909674aa1e510562efd9cb081f407c
