Make qemu use nova user

Libvirt 2.5 (latest version in cloud archive) seems to have changed
behavior of dynamic_ownership.

Change-Id: Icf9592c2f82f0f4a35074b9b13a51643a32631e9
Closes-bug: #1668654

ansible/roles/nova/templates/qemu.conf.j2

 stdio_handler = "file"
+
+{% if kolla_base_distro == "ubuntu" %}
+# TODO: this workaround need to be fixed in Pike
+# Ubuntu cloud archive released libvirt-bin version 2.5.0 which runs vms as
+# libvirt-qemu user. This locks access to nova created files for vms which
+# have permissions 722 for nova user. We need to force qemu to use this user
+# to be able to access vm files.
+# see https://bugs.launchpad.net/kolla-ansible/+bug/1668654
+user = "nova"
+group = "nova"
+{% endif %}