Fix compute CDM to include disabled compute node

Currently compute CDM excludes disabled compute node.
This patch set fixes compute CDM to include disabled compute node.

Change-Id: I8236bb73e0d9bb242251c2abfb59ad5693087afa
Closes-Bug: #1685787

watcher/common/nova_helper.py

@@ -82,6 +82,9 @@ class NovaHelper(object):
     def get_availability_zone_list(self):
         return self.nova.availability_zones.list(detailed=True)
 
+    def get_service_list(self):
+        return self.nova.services.list(binary='nova-compute')
+
     def find_instance(self, instance_id):
         return self.nova.servers.get(instance_id)