Add support for advanced grouping in dedibox inventory

[remyleone]

It would be helpful to have automated groups in dynamic inventory for ansible.
For instance, it would be helpful to have groups by: offer-id, groups by rpn capabilities and so on.
This could be helpful to have a set of filters that would ease migration depending on offer types.
As a customer it would mean being able to execute on playbook only on the server that got a particular offer enabled