added js/css and updated jinja template to do away with CDNs

[usmcamp0811]

I tried to use Graphene / Flask-Graphql today at work where I don't have internet access and ran into a problem with Graphiql requiring CDNs to work. I was able to resolve this eventually but wanted to have this in the main line so that I can keep things up to date and not have to worry about my hack at work breaking should we ever rebuild our environment.

[coveralls]

Coverage decreased (-3.1%) to 90.435% when pulling 334205496923ff4a467c3a086dc276dca43c5b6c on usmcamp0811:master into 0137ca1315d811a7e01a1d256e41c74bc1c3fc2c on graphql-python:master.

[acao]

If you want to ensure users are able to upgrade, and that this package doesn't have a fixed dependency, i might reccomend a non-runtime executed utility script to fetch the latest unpkg cdn bundle, and then cache the result in a gitignored path. you can target @latest (stable) and @next (pre-releases). That or a specific version fetched. Either way, this is already a great way to do offline support