Update to Apollo 2

[eric-burel]

Hi,
You can't call withRenderContext and register middleware using networkInterface anymore client side.

I am working on an update with Apollo 2, using Links. This needs some improvements because you can't add links on the fly with apollo 2.

See apollographql/apollo-client#4555

[eric-burel]

Hi @ochicf
Can you confirm me what this code is supposed to do:
https://github.com/OrigenStudio/vulcan-files/blob/master/lib/server/uploadMiddleware.js#L12

To my best understanding, it remaps the files in the query to the vulcan document content. However I am not sure what asyncBusboy is supposed to do? Calling it will lead to a BadRequestError: Missing multipart field ‘operations’ **(https://github.com/jaydenseric/graphql-multipart-request-spec)** error.

I may eventually ditch this middleware and directly improve the onInsert / onEdit handler, I don't know yet.