[Rpm-metadata] [Patch] createrepo --check option

[Hans-Peter Jansen]

Hi Seth,

as promised, here's my first patch for createrepo to suppress metadata 
recreation, if the timestamps are up to date, including documentation 
changes to createrepo.8 and ChangeLog. 

Works fine here, and I would be very happy to get it applied upstream.

If you have any issues with it, tell me, please.

Thanks,
Pete

P.S.: Could you say a few words to the message right above this one?
      Or to be more concise, can I use different group.xml files on
      different repos and any group definition in them with yum?