Fixed h tag to use the new background decorator API

cloudcontrol/node/host/tags.py

@@ -32,7 +32,7 @@ from cloudcontrol.common.client.tags import ttl, refresh, background
 
 @ttl(3600 * 24)  # one day
 @refresh(30)
-@background
+@background()
 def h():
     """Hostname tag."""
     return getfqdn()