Fix initial setup. Allow run with external IP

[pavlozt]

This change allows you to specify external IPs when they are not available from ansible facts.
Here's an example playbook:
variable hostname_fqdn must be defined in inventory

#!/usr/bin/env ansible-playbook
- name: Prepare app
  become: true
  hosts: etcd
  vars:
    etcd_ca_conf_directory: ./certs/
    etcd_ansible_group: "etcd"
    etcd_interface: eth0
    etcd_peer_port: "2380"
    etcd_client_port: "2379"
    initial_cluster_value: >-
      {% for host in groups[etcd_ansible_group] -%}
      {{ hostvars[host]['ansible_hostname'] }}=https://{{ hostvars[host]['hostname_fqdn'] }}:2380
      {%- if not loop.last %},{% else %}{% endif %}{%- endfor %}
  pre_tasks:
    - name: Set etcd_settings_user facts
      set_fact:
        etcd_settings_user:
          initial-advertise-peer-urls: "https://{{ hostvars[inventory_hostname]['hostname_fqdn'] }}:{{ etcd_peer_port }}"
          advertise-client-urls: "https://{{ hostvars[inventory_hostname]['hostname_fqdn'] }}:{{ etcd_client_port }}"
          initial-cluster: "{{ initial_cluster_value | trim }}"

    - name: Show debug info
      debug:
        var: etcd_settings_user
  roles:
    - githubixx.etcd

A practical case is if you run Etcd in the Internet or with multiple cloud providers