AsyncStorage as localStorage alternative on mobile #48

AsyncStorage lib behavior is almost completely like window.localStorage, except:

1. Is async. most such solutions are async. Not a problem, but is a complicated solution if all you want is a cookies alternative.
2. crashes (instead of return null) when you try to store a non-empty value.
3. Cannot store '', number, boolean, null, undefined. A simple wrapper fixes this.
4. Works for Android, ios
5. Default size limit 6MB, resizable through option

cred: 620k stars
npm: https://www.npmjs.com/package/@react-native-async-storage/async-storage
docs: https://react-native-async-storage.github.io/async-storage/