Interactive EntitySet Viewer

As a user, I would like a way to interact with an entityset so that I may:
- better understand the relationships between dataframes
- view the explanation, relationships, and provenance that created a feature

The SpaCy library implements a visualization layer called [DisplaCy](https://spacy.io/api/top-level#displacy.serve), that will start up a simple webapp, creating an interactive viewer so the user can interact with the language model they are working on. Featuretools could implement something similar