Android implementation

Additional info:

1. For default data store should probably use https://developer.android.com/reference/android/preference/PreferenceManager#getDefaultSharedPreferencesName(android.content.Context). Related SO question: https://stackoverflow.com/questions/26675159/what-is-the-file-name-used-by-default-shared-preferences

