Fix for: https://issues.apache.org/jira/browse/AMQ-4837 : LevelDB corrupted in AMQ cluster.

- Log rotation was causing a pre-mature index snapshot to be taken on the slave (snapshot while the slave was still synchronizing).
- Also fix issue with the append position displayed in JMX for the master not being correct.
https://issues.apache.org/jira/browse/AMQ-3725 - allow kahadb to recover from failed file system