Pub/Sub

basic implementation of pub sub pattern for golang with model sharing

The main idea is that inside the hemstreet folder, there are two modules ( foo / bar ). These two modules want to interact with each other but not create a circular dependency. So we go through the hub/hub ( sorry for the stutter ) package to be the mediator while using the models folder for a common package that does not import either of the two so we can have the same models.