MB-21568: Reconcile hashtable with disk following rollback

MB-21568: Reconcile hashtable with disk following rollback

After rolling back the disk store to the requested seqno a scan of the
vbucket's checkpoint must occur. Any item in the checkpoint with
a seqno > than the rollback must be dropped or rolled back.

+ A missing close is addressed by using a wrapper class that will
  RAII close each file opened in the rollback code.

Change-Id: Iabe43f59ed40931c1c97b65147b7a414d4ff7cc5
Reviewed-on: http://review.couchbase.org/69725
Reviewed-by: Dave Rigby <daver@couchbase.com>
Tested-by: buildbot <build@couchbase.com>