MB-100 Fix dbdump flag handling

Change-Id: I6660eff6d0c5c5b4acd5b92778bf73ee4ee282d2
Reviewed-on: http://review.couchbase.org/26792
Reviewed-by: Fulu Li <fulu@couchbase.com>
Tested-by: Aaron Miller <apage43@ninjawhale.com>