Refetch query when get any missing fields on cache

[joe-re]

Fix: #3928

I implemented to refetch when get any missing fields on apollo-cache-inmemory.
I gave refetch logic as callback from apollo-client to apollo-cache-inmemory because refetch is client context. I feel this is needed more discussions..
How do you think?

Checklist:

• If this PR is a new feature, please reference an issue where a consensus about the design was reached (not necessary for small changes)
• Make sure all of the significant new logic is covered by tests

[hwillson]

Thanks for this PR @joe-re. This has currently been addressed in React Apollo, through the use of the Query component's partialRefetch prop (see the React Apollo Query API docs for more info). We're looking at how refetching is handled across the board, and will be implementing future changes, but for now using partialRefetch will work. Thanks again!