[Model Request] Learning Graph Representations with Embedding Propagation

## 🚀 Feature
Hi, it would be awesome to implement [Learning Graph Representations with Embedding Propagation
by Alberto Garcia-Duran, Mathias Niepert ](https://arxiv.org/abs/1710.03059) for unsupervised learning on graphs.

## Motivation
It's a very useful unsupervised learning approach for learning graph representations without ground truth labels.
Additionally, the approach can be extended to operate with [missing features](https://arxiv.org/abs/1811.04752).