966027 - hiding ability to refresh a manifest if its not supported

Newer versions of candlepin produce manifests that contain an idCert field
with the key and cert of the distributor.  This allows manifests to be refreshed.
The current version of candlepin within Red Hat has not be upgraded to support this however
so some manifests (even ones generated today), will error with a nasty traceback if the
refresh button is clicked.  Here we check if the idCert is present within the candlepin
owner's upstream hash.