Summary:
Since `AsyncStorage` is the primary cache, it would be nice to stick with fetch's promise model and make the common use-case of:
1) check cache
2) make request if cache is invalid
more straightforward. Currently if I want to check a cache prior to using fetch (or another promise-based XHR lib) I have to provide a callback. I left the callback support and `resolve`/`reject` the promise after the callback has been applied.
Closes https://github.com/facebook/react-native/pull/593
Github Author: Rob McVey <mcvey@thecollective-la.com>
Test Plan: Imported from GitHub, without a `Test Plan:` line.
Rob McVey
Christopher Chedeau
Spencer Ahrens