Add support for notify periodic event of cluster.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1526409 13f79535-47bb-0310-9956-ffa450edef68
Correct the javadoc for Lifecycle interface.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1526412 13f79535-47bb-0310-9956-ffa450edef68