EXT-7901 FIXED: Follow up fix to remove short-term hack.

As advertized, I have removed the short-term hack that I put in place
to make release note URLs work. I have now put in place a more general
and correct solution. The key observeration from Roxie is that SLE
SLurls should have the same hostname as the grid host. So now, URLs
like http://google.com/app are no longer categorized as a SLurl and
produce errors when you click on them.