Merge: App.nit Data Store

Portable data storage services for app.nit.

May not pass the mnit_simple test before mergin the Intent PR #644.

Closes #559

Pull-Request: #662
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>
Reviewed-by: Frédéric Vachon <fredvac@gmail.com>