Calculate replicated log data size on recovery

Calculate replicated log data size on recovery

We maintain the replicated log data size at runtme but we should also
calculate the data size for recovered entries on startup.

I changed the AbstractReplicatedLogImpl#append method to also add to the
dataSize. Previously dataSize was adjusted in ReplicatedLogImpl#appendAndPersist
after it was persisted. I'm not sure why it was done this way but if
persistence failed then the entry would've been added to the in-memory
log without increasing the dataSize. This seems inconsistent - if we add
to the log we should always increase the dataSize.

The same with removing entries from the log - ReplicatedLogImpl re-calculated
the dataSize after it was persisted. So I changed removeFrom to adjust
dataSize and changed ReplicatedLogImpl#removeFromAndPersist to call
AbstractReplicatedLogImpl#removeFrom (code was duplicated).

To avoid out-of-band changes to dataSize I made it private. Same with
journal. I think this is safer - these should be owned by
AbstractReplicatedLogImpl and derived classes shouldn't modify these
directly.

Change-Id: I114cbac1d6a450bc0a1c8c6ee60042ad28a89bf4
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>