Bump Ansible to 2.3

List of changes needed by Ansible 2.3 release:

[virt.py module]:
- Since 2.3, autostart is now an indempotent VM attribute instead of a non
  indempotent forced autostart attribute set to True [1].
- We are now able to start the undercloud VM and configure it to be
  autostarted at virthost boot in one task instead of two.

[1] - 792efbe3b6

Change-Id: I096fb70faf0ec429e17047455bef9352d7995f34

requirements.txt

@@ -1,5 +1,5 @@
 ara
-ansible==2.2.0.0
+ansible==2.3.0.0
 netaddr>=0.7.18
 pbr>=1.6
 setuptools>=11.3

roles/libvirt/setup/undercloud/tasks/main.yml

@@ -278,22 +278,16 @@
     state: 'directory'
   when: non_root_chown|bool
 
-# Start the undercloud virtual machine.
-- name: Start undercloud vm
+# Start the undercloud virtual machine and configure it to be
+# automatically started at boot.
+- name: Start undercloud vm and configure it to be autostarted at boot
   virt:
     name: "{{ undercloud_node.name }}"
+    autostart: True
     command: start
     state: running
     uri: "{{ libvirt_uri }}"
 
-# Configure the undercloud virtual machine to be
-# automatically started at boot.
-- name: Configure undercloud vm to start at virthost boot
-  virt:
-    name: "{{ undercloud_node.name }}"
-    command: autostart
-    uri: "{{ libvirt_uri }}"
-
 # Get the ip address of the undercloud.  This will retry several times
 # (`undercloud_ip_retries`) until the undercloud is ready.  The script
 # works by getting the MAC address of the first undercloud interface,