Add workaround to fix centos-binary-deploy gate

The RDO nova package is missing a dependency on oslo-policy and this is
breaking our centos-binary-deploy gate. Install the missing package in
nova-base until the issue is fixed upstream.

Change-Id: Iece7edd754c6f173635b0e0c437a998f3b9492d3
Closes-Bug: #1525502

docker/nova/nova-base/Dockerfile.j2

@@ -4,10 +4,13 @@ MAINTAINER {{ maintainer }}
 {% if install_type == 'binary' %}
     {% if base_distro in ['centos', 'fedora', 'oraclelinux', 'rhel'] %}
 
+# TODO(mandre) remove python-oslo-policy once RDO package is fixed
+# https://github.com/openstack-packages/nova/blob/rpm-master/openstack-nova.spec
 RUN yum -y install \
         openstack-nova-common \
         python-keystoneclient \
         python-cinderclient \
+        python-oslo-policy \
         python-nova \
         bridge-utils \
     && yum clean all