MB-100 Fix dbdump memory leak

Change-Id: If5a6fe4d7cb2a8a084c72fa119b9c71264d1ffb7
Reviewed-on: http://review.couchbase.org/26793
Reviewed-by: Fulu Li <fulu@couchbase.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>
Tested-by: Aaron Miller <apage43@ninjawhale.com>