[torch vitals] move into namespace and fix windows tests
Summary:
as in title
resolves D25791248 (https://github.com/pytorch/pytorch/commit/069602e028d01b5287f719ccd8fae02026842a05)
Test Plan: buck test //caffe2/aten:vitals
Reviewed By: EscapeZero, malfet
Differential Revision: D26090442
fbshipit-source-id: 07937f246ec0a6eb338d21208ada61758237ae42
