The RHEL/Fedora server package is openssh-server

Not openssh. Both the client and server packages depend on openssh so
it is not necessary to state this one explicitly. This probably went
unnoticed for so long because openssh-server is installed as part of
the @core set.
Merge pull request #43 from chewi/rhel-package

The RHEL/Fedora server package is openssh-server