Add support for the uscms and hcc repos in osg-promote.

This adds a new route for the hcc repos.  If uscms wants to have a testing / release split, they'll also need the changes to the get_tag function.

Note that this could support the OSG 3.1 / 3.2 split if we kept the name of the "primary" release tags to "osg-release" and just added new routes for OSG 3.1.  Otherwise, we'd need an osg-build release per major version (which, considering, is not that horrible).