When will we implement the `deleteAll()` method?

[huan]

I need this method to reset my local graphcool dev server(docker) because gc local reset does not work now.

https://github.com/graphcool/graphcool-lib/blob/8ae6365ebb9db962198162ea09a912d961fe8821/src/index.ts#L131

See: https://github.com/Chatie/graphql/issues/3