Clean-up resources when stopping the service

[xtor]

When the service is stopped, the interface should be returned to its original state, or at least to one close to it. E.g.:

• All the streams and the resources allocated to them will be cleaned up
  • Depends on Add remove_talker method #15
• All the device tuning performed will be reverted (e.g. EEE will be re-enabled)
• Any qdisc mappings, VLAN associations, etc, will be removed
• Etc