Add ability to specify custom node name in reclass.

In terms of PR to salt formula:
https://github.com/salt-formulas/salt-formula-salt/pull/44
I would like to introduce this changes in model.
diff --git a/salt/control/cluster/openstack_proxy_single.yml b/salt/control/cluster/openstack_proxy_single.yml
index fcfa885..8ad0baf 100644
--- a/salt/control/cluster/openstack_proxy_single.yml
+++ b/salt/control/cluster/openstack_proxy_single.yml
@@ -13,6 +13,7 @@
           engine: virt
           node:
             prx01:
+              name: ${_param:openstack_proxy_node01_hostname}
               provider: ${_param:infra_kvm_node01_hostname}.${_param:cluster_domain}
               image: ${_param:salt_control_trusty_image}
               size: openstack.proxy