Add a disabled: true attribute to services

All the attribute does right now is, it will skip host allocation for
the service.

plugins/inventory/float.py

@@ -522,7 +522,9 @@ class Assignments(object):
             service = services[service_name]
             available_hosts = cls._available_hosts(service, group_map)
             num_instances = service.get('num_instances', 'all')
-            if num_instances == 'all':
+            if service.get('disabled'):
+                service_hosts = []
+            elif num_instances == 'all':
                 service_hosts = sorted(available_hosts)
             else:
                 service_hosts = sorted(_binpack(
@@ -530,7 +532,7 @@ class Assignments(object):
             service_hosts_map[service_name] = service_hosts
             for h in service_hosts:
                 host_occupation[h] += 1
-            if service.get('master_election'):
+            if service.get('master_election') and not service.get('disabled'):
                 if 'master_scheduling_group' in service:
                     available_hosts = set(available_hosts).intersection(
                             set(group_map[service['master_scheduling_group']]))