Bug 1446: Add JMX stats for in-memory data store

    Added stats, available via JMX,  to track data for the various thread
    pool executors used by the in-memory data store. Also added commit stats.

Change-Id: Ica8dff7aef8989f2b23b1fc8c100a535998273b1
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>
Merge "Bug 1446: Add JMX stats for in-memory data store"