Add ability to override proxy_node01 address via soft param

Change-Id: I2cdbcfde29af97e24fc498eaa43355d807804cf8
diff --git a/reclass/storage/system/openstack_dashboard_single.yml b/reclass/storage/system/openstack_dashboard_single.yml
index 51e2d91..00bd6a8 100644
--- a/reclass/storage/system/openstack_dashboard_single.yml
+++ b/reclass/storage/system/openstack_dashboard_single.yml
@@ -2,6 +2,7 @@
   _param:
     openstack_proxy_hostname: prx01
     openstack_proxy_system_codename: trusty
+    openstack_proxy_node01_address: 172.16.10.121
   reclass:
     storage:
       node:
@@ -13,4 +14,4 @@
           params:
             salt_master_host: ${_param:reclass_config_master}
             linux_system_codename: ${_param:openstack_proxy_system_codename}
-            single_address: 172.16.10.121
+            single_address: ${_param:openstack_proxy_node01_address}