* core: return response object from runHttpQuery
* core: change gqlResponse to graphqlResponse and add custom RequestInit type
* core: add cache-control headers based on the calcualted maxAge
* core: add extensions check during cache-control header creation
* core: create headers when cacheControl is not enabled otherwise pass through extensions
* express: initial tests of CDN cach-contol headers
* core: fixed tests with applyMiddleware and pass cacheControl config
* core: cache hint fixes, ignore when no maxAge, and check for rootKeys
* core: check for hints of length 0
* core: node 10 fails file upload test for some stream reason
* docs: add cdn caching section to features
* add space after // in comments
* fix feedback: proxy alignment and response creation
Adds cache-control toggles for http header calculation and stripping out
the cache control extensions from the respose.
Brings the default calculation of headers in line with the proxy.
* fix links in comments
* fix tests with null dereference
* update cdn docs and migration guide to include latest cdn configuration
* add not for engine migration to set engine to false
* add engine set to false in migration guide
* express: fixed tests
* address feedback to use omit and documentation
* docs: cdn caching is alternative to full response caching
* add back epipe check in upload tests
