Rudder

We want to assign a "state" tag for nodes, which can then be used to decide Rudder behavior on several aspects, mainly:

- are they special rules to apply to the node ?
- are policies updated for that node?
- does the node takes part of aggregated compliance?

Ideally, of these aspects should be configurable by the user for each state (appart from "default" which must be identical to what a node state is on rudder today).

The status list should be extensible, but we want at least:

- init (an initializing state that could be automatically set just after node acceptation, or before the first inventory comes once we get the possibility to pre-define nodes)
- enabled / default: the default status for a node,
- decomissionning: meaning that the node is still managed by Rudder, but that it will be removed at some point (and so, perhaps some special rules should be applied).
- disabled : when a node should not be managed by Rudder. Mainly, that mean that the node doesn't have new policy generated for him, nor that it should be part of the aggreagated compliance reports

All these state are different from the action of deleting a node.

This ticket is just here to implements the data structures and internal algo.