As a user I want to have tree folders by default and I want to keep my folders arborescence save

[fabienmoyon]

CURRENT

By default it's flat folders and we know it's not hard to use when we have some folders tree structure.
To have tree folders in Inbox we need to activate it in the configuration :

The tree structure is currently not save, not in the OpenPaaS backend, not in a cookie and not in James

EXPECTED

Save the tree structure and for this we need to discuss first with the James team to see where they want to have it, frontend or backend side and if it's interesting for them in James