Datasette-render-binary

- Updated for compatibility with latest Jinja. [4](https://github.com/simonw/datasette-render-binary/issues/4)

Now uses the [filetype](https://pypi.org/project/filetype/) module to suggest a possible format.

<img width="600" alt="many-photos-tables__RKFaceCrop__58_rows" src="https://user-images.githubusercontent.com/9599/59449428-df85cf00-8dbb-11e9-8817-0fd09ff539c7.png">

Added screenshot.