BabuDB: incremented version number. added a GlobalSyncListener for the "optimistic" replication.

DiskLogger: added a mechanism to register a listener for the event that the queue runs empty.
ReplicationConfiguration: added the "optimistic"-flag to allow eventually  consistency.
Database: changed interface because of the "optimistic"-flag. added a mechanism to update a Database by replacing its LSMDatabase instance.
DatabaseManager: fixed a bug depending on the reseting of Databases while a Replication-Load.
DBConfig: added a reset method.
LatestLSNUpdateListener: added a failed() method to cancel requests when shutting down the replication.
ReplicationManager: added isMaster() and halt() method (used set the replication into sleep-mode).
Replication: fixed some bugs depending on the master-fail-over mechanism.
RequestDispatcher: introduced a atomic internal state.
SlaveStates: fixed a bug caused by a race-condition.

git-svn-id: https://babudb.googlecode.com/svn/trunk@180 d4c7dd96-b7b2-11dd-893d-d98698f66bbf