Switch to use "yum upgrade" instead of "yum upgrade-to".
Switch to use "yum upgrade" instead of "yum upgrade-to".

Apparently this is one case where CentOS and RedHat differ, the latter
doesn't support that command.

As long as we always pass in a version, both commands are equivalent.

maciejmrowiec/masterfiles,maciejmrowiec/masterfiles,frap/masterfiles-1,martingehrke/masterfiles,martingehrke/masterfiles,martingehrke/masterfiles,phnakarin/masterfiles,maciejmrowiec/masterfiles,frap/masterfiles-1,phnakarin/masterfiles,phnakarin/masterfiles,frap/masterfiles-1