Bug#853914: preliminary packaging is available

[lumin <cdluminate@gmail.com>]

The preliminary packaging for pytorch and pytorch-contrib
is available here: https://github.com/CDLuminate/pytorch

pytorch packaging is held by the `debian` branch, while
the pytorch-contrib packaging is held by the `debian-contrib`
branch.

The remaining works to be done are:

* disable nearly all stuff related to SIMD for compatibility.
* deal with the library rpath issue.
* make pytorch's libraries private. pytorch shares
  the same backend code with torch7 but they use different
  TH_INDEX_BASE variable, that is to say they cannot share
  the shared object files.
  See: https://github.com/pytorch/pytorch/issues/640
* ...