GitLab

* tentatively fixing the cpu version of circleci jobs, now pipe tests are the last ones standing
* fixing oss backcompat, trying to fix rpc in old pytorch also
* fixing the file based init in torch 1.5

* add additional unit test
* support model parallelism in oss

* lintfixes

* come on black

* Update tutorial_pipe_multiprocess.py

make RANK global like the other tutorials
Co-authored-by: Vittorio Caggiano <caggiano@gmail.com>

Adds support for:
* Reused layers (e.g. for weight sharing)
* Lazily-constructed layers
* Single-process control via PipeRPCWrapper
* PipelineStyle.AsyncScheudle, which lays the foundation for asynchronous pipeline work by introducing an event loop for each rank/worker to process either activations or gradients as they arrive

Also added examples for multi-process and PipeRPCWrapper