Create %name.rpm symlink to release RPM for each repo

I'd like to make it easier to configure scl.org repos programmatically, without needing to know the version/release numbers used for the release RPMs.  This adds a symlink, e.g. "rhscl-ruby193-epel-6-x86_64.noarch.rpm" to the newly built release RPM.

This code is untested - sorry!