Opt-in package overblog/graphiql-bundle

[deeky666]

Hi,

I wonder why the overblog/graphiql-bundle package is required by default. Personally I don't use/need it but have to download it through composer nonetheless.

Maybe we could make it opt-in?

[andrew-demb]

👍
Please open a PR to make it an optional dependency.

See also #206