In order to enable define in Cluster element, ClusterSingleSignOn implements ClusterValve.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc8.0.x/trunk@1645596 13f79535-47bb-0310-9956-ffa450edef68
Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=57324
If it is known that the connection is going to be closed when committing the response, send the connection: close header.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc8.0.x/trunk@1645627 13f79535-47bb-0310-9956-ffa450edef68