Add metadata support for gateway and compute

Without this, Heka isn't properly configured on gateway and compute
nodes.

Change-Id: Ia18df36ea198458828aa5386eb42d386de0eea5e

metadata/service/compute/single.yml

@@ -1,5 +1,7 @@
 applications:
 - neutron
+classes:
+- service.neutron.support
 parameters:
   neutron:
     compute:
@@ -24,5 +26,3 @@ parameters:
         mechanism:
           ovs:
             driver: openvswitch
-
-

metadata/service/gateway/single.yml

@@ -1,5 +1,7 @@
 applications:
 - neutron
+classes:
+- service.neutron.support
 parameters:
   neutron:
     gateway:

neutron/meta/collectd.yml

@@ -1,4 +1,4 @@
-{%- if pillar.neutron.server %}
+{%- if pillar.neutron.server is defined %}
 {%- from "neutron/map.jinja" import server with context %}
 {%- if server.get('enabled', False) %}
 local_plugin: