Preview diff for Jupyter notebooks

Description

The diff view for Jupyter Notebook files (.ipynb) does not render and previsualize the diff, instead it shows the JSON, JS, etc, contents of the notebook.

In other previews in Gitlab, of entire files -- not diffs-, notebooks are rendered previsualized.

Proposal

I propose to to use the nbdime tool to render previsualize diffs of notebooks.

Links / references

• http://nbdime.readthedocs.io/en/stable/
• https://twitter.com/betatim/status/996328764622692352