Basic reference pytorch implementation of GraphSAGE.
Forgive the messiness; it was coded in a rush.

Execute `python -m graphsage.model` to run the Cora example.
It assumes that CUDA is not being used, but modifying the run functions in `model.py` in the obvious way can change this.
There is also a pubmed example (called via the `run_pubmed` function in model.py).
