Rated 5 out of 5 stars
Prism allows https exceptions. Just not when adding new Prism apps in the dialog. Just proceed anyway, and when the site opens in a Prism window, it will allow you to set exceptions.
Could stand to support it on the dialog though, because I can't get the favicon! Also, it seems Prism itself has lost its prism-icon.
But all that is irregardless of this really convenient extension, to which I give a high-five!