VUE_APP_GRAPHQL_TOKEN is still in client code

We've moved this to zeit.co so we can define the API token on the server, and proxy requests through this server implementation rather than straight to `api.github.com`. But we're still bundling `VUE_APP_GRAPHQL_TOKEN` into the `app.js`, which kinda defeats the purpose of hosting on zeit.co :) @robbieaverill 