Graphiql doesn't load in offline environment

[aviadavretz]

Because these two scripts can't be downloaded:

    <script src="//unpkg.com/subscriptions-transport-ws@0.8.3/browser/client.js"></script>
    <script src="//unpkg.com/graphiql-subscriptions-fetcher@0.0.2/browser/client.js"></script>

[aviadavretz]

Opened a PR.

@oliemansm
Please take a look, it prevents me from updating to the latest version :(

[oliemansm]

@aviadavretz Thanks for the PR, just merged it!