Backport r1584267, r1584268, r1584270 and r1584274
Add support for cross context session replication to BackupManager.
This fix is included sevral improvement of cluster manager.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1584275 13f79535-47bb-0310-9956-ffa450edef68