Network action recreates port every time it is run (with same parameters)

Summary

Shade os_port module used for [port creation] (tasks/network_port_create.yml) does not work idempotently in certain conditions - when port that is being created gets address from subnetwork pool.

Steps to reproduce

openstack_ports:
- name: "my-port"
  network: "my-network"
  addresses: ["my-subnetwork"]

Expected behavior

Port should not be recreated when role is used with the same parameters.

Actual behavior

Each time openstack role (network action) is run (with exactly same parameters) port is recreated, getting different IP address.

Possible fixes

Run os_port only when port does not already exists (port name check).