BOOKKEEPER-218: Provide journal manager to manage journal related operations
Review Request #4737 - Created April 16, 2012 and updated
Currently we put all journal related operations in Bookie class. It would be better to provide a journal manager to provide journal related operations. It would make Bookie logic more clearly. Besides that, some admin tools like BOOKKEEPER-183 needs to provide could use JournalManager to read/check journal files directly.