Network ACLs management

[MOBergeron]

Hello,

I've noticed that the management of the network ACLs is lacking in the project. It is still possible to attach ACLs to an instance via the config["devices"]["name_of_nic"] but it is not possible to create, delete, etc. an ACL. Same goes for the network ACL rules.

This feature would be a great addition to the project.

[MOBergeron]

I've added the functionality but currently lack the time to update the documentation and add the unit tests. Here's the changes for Network ACLs https://github.com/MOBergeron/pylxd/tree/feature/network-acls-management.

I'm only posting this here to make sure no one else waste their time doing it as it is already done and working.