Allow for specifying name instead of host as per the documentation at http://docs.ansible.com/known_hosts_module.html

lib/ansible/modules/extras/system/known_hosts.py

@@ -82,7 +82,7 @@ def enforce_state(module, params):
     Add or remove key.
     """
 
-    host = params["host"]
+    host = params["name"]
     key = params.get("key",None)
     port = params.get("port",None)
     #expand the path parameter; otherwise module.add_path_info