I'm reverting apollographql/apollo-server#1698 not because it's been problematic in any way, but because I'd like to give it a bit more thought and don't want this to accidentally get cut into a release prior to that consideration.
More specifically: The `graphql-tools` update on its own shouldn't really cause any problems, but the [4.x version of `graphql-tools`](https://github.com/apollographql/graphql-tools/releases/tag/4.0.0) is intended to support and enable the latest `graphql@14` which contains [breaking changes](https://github.com/graphql/graphql-js/releases/tag/v14.0.0).
I believe most of those breaking changes would be show-stoppers and the failures would surface immediately (meaning that servers would completely fail to start, rather than being a surprise in other, more delayed scenarios), but it's still worth pausing and carefully considering versioning to avoid any surprises.
That said, the 14.x version of `graphql` has been an acceptable range in the `peerDependencies` of `apollo-server-*` since before its final release came out, and I don't believe we've caught wind of anything that a major version bump would have prevented or made more clear. In the end, `graphql` is a peer dependency and any problems should only surface if consumers also update their `graphql` dependency — a clear major version bump, which deserves review by the upgrader — so perhaps we can avoid bumping the major version after all?
Input welcomed, but again, merging this now to give this a bit more thought first.
cc @hwillson
* Initial implementation of Apollo Server 2 for gcf
* First try at running with tests
* Updated naming
* Removed lambda mentions
* Simply use referer
* Updated README
* Updated Changelog
* Renamed gqlApollo to googleCloudApollo
* Added more details
* Removed extra check
