Simplify the code of o.a.c.ha.tcp.SimpleTcpCluster.
In order to add or remove cluster valve to Container, use pipeline instead of IntrospectionUtils.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1584505 13f79535-47bb-0310-9956-ffa450edef68
Set null rather than this.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1584507 13f79535-47bb-0310-9956-ffa450edef68