add python-netaddr so ipaddr filters can be used in ansible playbooks

Change-Id: If40a044c57476469f8a5579a81a26156780cd5df
diff --git a/provisioner/Dockerfile b/provisioner/Dockerfile
index 327a813..a0cdd14 100644
--- a/provisioner/Dockerfile
+++ b/provisioner/Dockerfile
@@ -44,7 +44,7 @@
 	apt-get install -y  software-properties-common && \
 	apt-add-repository ppa:ansible/ansible && \
 	apt-get update -y  -m && \
-	apt-get install -y git ansible
+	apt-get install -y git ansible python-netaddr
 
 RUN mkdir -p /root/.ssh
 COPY ssh-config /root/.ssh/config