Restoration of interfaces status in the host after deleting an instance scenario

[alogracia]

Frequently, after deleting an instance scenario, interfaces in the host remain in down state. This generates problems when deploying a new instance scenario that uses those interfaces: the interfaces must be up in the host for the guest to be able to use them.

Openmano should restore the static configuration of the host interfaces when they are freed, UP state and MTU size at least.