BabuDB/Java/replication: Changed the way the drift was calculated by assuming...

BabuDB/Java/replication: Changed the way the drift was calculated by assuming it includes one half of the RTT it took to retrieve the remote time.

git-svn-id: https://babudb.googlecode.com/svn/trunk@623 d4c7dd96-b7b2-11dd-893d-d98698f66bbf