updater not ask for master root password unless needed

When updating a slave server, the updater always prompts for the master's mysql root credentials, even when not needed.

We should first query the master using dbmaster connection info for the current server.dbversion - if there is an sql update available, the credentials will be needed. If there is not an sql update, the credentials should only be asked for if answering yes to Reconfigure Permissions in master database?.