Wip entity components

![Breaking Changes!](http://i.imgur.com/dvLD5Gp.jpg)

This PR changes a lot of stuffs in how data are stored in the database.
To prepare for the future, users and papers are stored using [entities and components](https://en.wikipedia.org/wiki/Entity_component_system). This will later allow for modular data brought by different bundles without impacting other components.

As an example, the new role and phase model is saved as components attached to a paper entity.

Upgrading to this version will break existing installations, please consider making backups if you had one. However this is still a beta version so it should not be critical.