lib/app: app is a group

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib: intro of app::data_store

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
android: intro android_store

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib: intro the linux implementation of app.nit

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib/linux: implement app::store using sqlite/json/basedir

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
mnit_simple: minimal test of data store

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>