We can't use `apollo-server-env` as a project reference because that requires `composite: true`, and that implies `declaration: true`, which doesn't work for `apollo-server-env` because we need to write our own declaration files for re-exported imports.
This commit also removes `apollo-engine-reporting-protobuf` as a reference, which errored out because it doesn't actually contain any TypeScript code.
* Enable declarationMap in tsconfig.json
See http://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-9.html
* Add apollo-server-caching package and improve typings
* Remove superfluous test steps
* Add .npmignore to apollo-server-caching
* Add apollo-server-env and apollo-datasource-rest packages
* Fix broken imports
* Use prepublish instead of prepare
* cache is now passed to data sources from ApolloServer constructor
* fix Object.values to use the object passed in rather than this
* add initial datasource test
* docs: initial data source documentation
* docs: initial data source documentation
* compiles and documentation now highlights code in data-sources.md
* Some changes to the data source docs