update /etc/hosts and system level

Change-Id: If14e63ad26c5a3fc915680c8e3569dfba526297a
diff --git a/classes/cluster/virtual-mcp10-contrail/openstack/init.yml b/classes/cluster/virtual-mcp10-contrail/openstack/init.yml
index d00d8e7..5e746a4 100755
--- a/classes/cluster/virtual-mcp10-contrail/openstack/init.yml
+++ b/classes/cluster/virtual-mcp10-contrail/openstack/init.yml
@@ -72,6 +72,7 @@
     ceilometer_influxdb_password: lmapass
   linux:
     network:
+      purge_hosts: true
       host:
         prx:
           address: ${_param:openstack_proxy_address}