Symlink to redhat-uep.pem if we seem to be syncing a CDN hostname cert dir.

The CDN CA cert is required if we're going to communicate with cdn.redhat.com
or cdn.stage.redhat.com. We decided to watch for hostnames like these in the
plugin, and if spotted we'll make sure there's a symlink to
/etc/rhsm/ca/redhat-uep.pem, assuming it exists.
Code cleanup.